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A Computer Program in QuickBASIC

for the Heuristic Design

of Looped Water Distribution

Networks

User Instructions for
LOOP Version 4.0

Prasad M. Modak
Juzer Dhoondia

UNDP/WORLD BANK

ASIA Water Supply and Sanitation Sector Development
Project, RAS/86/160, December 1991

The International Bank for Reconstruction and Development / The World Bank
1818 H Street, N.W.
Washington, D.C. 20433, U.S.A
All rights reserved

Manufactured in the United States of America

This is a document published informally by the World Bank. In order that
the information contained in it can be presented with the least possible delay, the
typescript has, not been prepared in accordance with the procedures appropriate to
formal printed texts, and the World Bank accepts no responsibility for errors.

The World Bank does not accept responsibility for the accuracy of text and
computer software and the views expressed herein, which are those of the authors and
should not be attributed to the World Bank or to its affiliated organizations. The
findings, interpretations, and conclusions are the results of research supported by the
Bank; they do not necessarily represent official policy of the Bank. The designations
employed, the presentation of material, and any maps used in this document are solely
for the convenience of the reader and do not imply the expression of opinion whatsoever
on the part of the World Bank or its affiliates concerning the legal status of any country,
territory, city, area, or of its authorities, or concerning the delimitation of its boundaries
of national affiliation.

Dr. Prasad, M. Modak is Associate Professor at the Center for Environmental
Science and Engineering at Indian Institute of Technology, Bombay, India and Mr. Juzer
Dhoondia is Project Engineer at the same institute; Dr. Modak specializes in applications
of modeling and systems analysis tools to environmental engineering problems and has
more than 50 publications and reports to his credit. He has completed several consulting
assignments in India for industries, state and federal agencies, and for international
agencies like United Nations Environment Program (UNEP), Educational, Scientific and
Cultural Organization (UNESCO). Mr. Dhoondia has been assisting Dr. Modak in
projects involving software development on PC platform.

Acknowledgements

We would like to express our sincere thanks and appreciation to Mr. Terry Hall,
Project Manager, and Mr. Shyamal Sarkar, National Country Officer, of the Asia Water
Supply and Sanitation Sector Development Project for their contribution, support, and
encouragement in the software development, and in the preparation of the manual.

Special thanks are extended to the following agencies, officials and experts, and
to the World Bank for their kind assistance, time, and effort in providing information as
well as in sharing their useful views and comments on the manual.

- Ministry of Urban Development, Government of India, New Delhi;

- Central Public Health and Environmental Engineering Organization,
Government of India, New Delhi;

- Indian Institute of Technology, Bombay;

- Dr. Paul Hebert;

- Mr. Daniel del Puerto, Local Water Utilities Administration, Philippines;

- Mr. Steve Maber, The World Bank;

- Dr. Kiran Bajracharya, Department of Water Supply and Sanitation,Kathmandu;

- Asia Water Supply and Sanitation Sector Development Project staff in
Bangladesh, India, Nepal and Pakistan.

Special thanks are also extended to Ms. Premjit Dhillon of ASTIN for her
contribution in editing the report; to Mr. Steven Cameron, Mr. Bill Fraser, Mr. Jonathan
Miller, and Ms. May Eidi of the World Bank Group Composition Unit for their
contribution in design and typography; and to the RAS/86/160 project's support staff in
New Delhi for their assistance in typing.

PREFACE

This document is a part of a package of three microcomputer programs and
user instructions prepared by Asia Water Supply and Sanitation Sector Development
Team (SDT) for computer-aided planning and design of low-cost water supply and
wastewater disposal systems in developing countries. It is concerned with the
program LOOP Version 4.0 (contained on diskette #2) which uses Newton-Raphson
technique and the Hazen-Williams or Darcy-Weisbach flow equations for the heuristic
design of looped distribution networks. Version 4.0 handles up to 1000 pipes and 750
nodes as well as multiple sources with fixed or variable heads, fixed or unknown
flows, booster pumps, check valves and pressure regulating valves. This program
also shows hydraulic gradelines along chosen sections and calculates headlosses,
velocities, valve operation status, pumping heads, etc. and costs. The program has
been designed for easy entry, storing, editing, and updating of data. It is provided in
compiled QuickBASIC form to speed program execution.

The program is not copy protected. However, the program should not be copied
for sale or for use by non-recipient without the prior written consent of the UNDP /
World Bank Regional Project RAS/86/160.

While developing the current version, due consideration was given to the
various comments received from the users on the LOOP program released in December,
1985 by the UNDP Interregional Project INT/81/047 in a package of microcomputer
programs; and the present version is expected to better meet the user requirements.
However, as the operation of a software is constrained by the hardware in use, all
attempts have been made to develop a software which is powerful, as well as
compatible with the hardware in use in the developing countries, in general.

The programs are intended solely for use by experienced planners and
design engineers; they presume that the user is familiar with such specialized topics
as hydraulics, mathematical optimization techniques, etc. The user instructions are
limited to information about the use of the programs, and also contains a brief technical
note on design principles and equations. However, they are not intended to inform
the inexperienced user on, for example, how to layout a pipe network. User
instructions . include references to the source material.

SDT extends thanks to one and all whose comments encouraged it to launch
another effort to bring out a software which would meet most of the user's
requirements. The lead, in this regard, given by the SDT field office in India is highly
appreciated.

SDT is interested in receiving information on the performance of these programs
in the field and suggestions for their improvement. This information will form the basis
for future modifications of the programs. All communications, in this regard, should be
addressed to the Infrastructure Division, Asia-Technical Department, The World Bank,
1818 H. Street N.W., Washington, D.C., 20433, U.SA

Carlo Rietveld
Principal Engineer

User Instructions for LOOP (Version 4.0)
Table of Contents

Title Page Number

PART - 1

1.0 Introduction 1

2.0 General Data Requirements 4

3.0 Hardware Requirements 4

4.0 Installation Procedure 5

4.1 Installation on PC with Twin Floppy Drive 5

4.2 Hard Disk Installation for IBM-PC / XT or AT 6

4.3 Use of the Program 6

4.4 Setting up LOOP using Command Line Options 8

5.0 LOOP Session 10

5.1 Configuration Screen 11

5.2 Main Menu 13

5.3 File Menu 15

5.4 Simulate and Display Results 22

5.5 Network Design 29

PART-II

6.0 Creation of TEST data file . 32

6.1 Definition of Node and Pipe 32

6.2 Numbering Technique 33

6.3 Resetting Configuration 33

6.4 Data Editor Environment . 35

6.5 General Information (Scr-I) 38

6.6 Pipe Data (Scr-II) 41

6.7 Node Data (Scr-III) . 42

6.8 Number of Fixtures (Scr-IV) 43

6.9 Fixed Head Reservoir Node Data (Scr-V) 44

6. 10 Variable Head Reservoir Node Data (Scr- VI) 45

6.11 Description of Booster Pumps (Scr- VII) 46

6.12 PRV Description (Scr- VIII) 47

6.13 CV Description (Scr-IX) 47

iii

6.14 Commercial Diameters (Scr-X A XI/XlI) 48

6.15 Design Information (Scr-XEI) ' 49

6.16 Check Data File 50

6.17 Solve TEST Network 51

6.18 Computation Time Required 52

7.0 Technical Description 54

7.1 Simulation 54

7.1.1 Newton Raphson Method 55

7.1.2 Initialization of Flows . 58

7.1.3 Minimization of the Bandwidth 59

7.1.4 Source Nodes 59

7.1.5 Pressure Reducing Valves and Check Valves 60

7.2 Pipes with Different Materials/Pressure Classes , 62

7.3 Parallel Pipes 64

7.4 Network Geometry Constraints 64

7.5 Design 64

7.5.1 Pipe Sizing Algorithm 65

References 69

Appendix A : Input and Output of DEMO.LOP 71

Appendix B : Input and Output of TEST.LOP 79

List of Figures

Title

Page Number

Configuration Screen

Main Menu

File Menu

DEMO Water Distribution Network

File Selection Screen

Simulation Messages

Display Menu

Results Menu

HGL for DEMO Network

10.

TEST Water Distribution Network

11.

Newton's Method of Finding Roots of an Equation

12.

Example of Setting Energy Equations for PRV

LOOP Version 4.0

Appendix A

LOOP

Version 4.0
Input Data File: DEMO.LOP

Program for Design of
Looped Water Distribution Network

and

Output Data File

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

User Instructions for LOOP (Version 4.0)

PART-I

1.0 Introduction

LOOP Version 4.0 is an entirely new version of the earlier program LOOP
Version 3.0 (written in IBM BASIC) developed and distributed under the joint efforts of
UNDP/World Bank. Apart from LOOP, UNDP/World Bank distributed another program
called FLOW (written in Microsoft FORTRAN 4.0). FLOW has more features and
capabilities than LOOP (Version 3.0) but is far less user friendly for regular use. LOOP
Version 4.0, in addition to other technical details, has exploited part of the code of FLOW
an4 at the same time enhanced the user interface to result into a more powerful and
effective program.

LOOP (Version 4.0), herein referred to as LOOP, could be used for the design and
simulation of new, partially or fully existing gravity as well as pumped water
distribution systems. It allows for reservoirs (fixed head or variable head viz. pumps),
valves (pressure reducing or check valves) and on-line booster pumps. LOOP has been
programmed in Microsoft QuickBASIC. Highlights of the improvements made in LOOP
are given below.

1. LOOP (Version 3.0) handles networks up to 500 pipes and 400 nodes whereas the
LOOP is capable of designing networks up to 1000 pipes and 750 nodes. This is expected
to help in achieving a direct one step design of the water distribution networks for even
large size towns as against the present situation requiring fragmentation.

2. LOOP (Version 3.0) does only an analysis or simulation of specified water
distribution network. The user has to provide the pipe diameters and the program
computes flows in pipes, pressures at nodes and the pipe costs. For a medium to large
size water distribution network, it becomes very difficult for the user to identify the best
combination of pipe sizes, which meets all the desired constraints and yet correspond to
a reasonably low cost. The procedure generally followed is then of typical trial and error
requiring a number of runs of the program.

LOOP automatically sizes the pipe diameters and thus relieves the user from the
burden of making a correct choice. The strategy to size diameters is heuristic and can be
effectively controlled by the user based on preferences and judgment. The strategy has
been found to yield almost optimal or near optimal network designs. A comparison
between the designs obtained using such a strategy and the designs obtained using
gradient search technique has shown quite favorable results.

In addition to the automatic pipe sizing option, LOOP allows the user to directly
specify the choice of pipe diameters. In this feature, the user is able to force the pipe to
follow a certain diameter rather than leaving it to the pipe sizing algorithm used in
LOOP. Similarly, the user can specify where parallel pipes are to be provided, and LOOP
sizes these pipes so as to meet the required node pressures.

3. LOOP (Version 3.0) uses only Hazen-William's formula as a hydraulic model.
LOOP allows for Darcy Weisbach expression as well.

4. LOOP (Version 3.0) uses the Hardy-Cross method of analysis to balance the flows
and pressures in the distribution system. This method works well for relatively small
networks but it is not recommended for medium to large networks since it is
computationally rather slow and does not guarantee convergence. LOOP uses the
Newton-Raphson method of balancing which is computationally much faster and has
better convergence properties.

5. LOOP (Version 3.0) considers only fixed head reservoirs and not variable head
reservoirs such as pumps. Further, it did not have provision to allow elements such as
pressure reducing valves, check valves and on-line booster pumps. LOOP considers
inclusion of all these aspects in the water distribution system.

6. LOOP (Version 3.0) does not mark the existing pipes in the system explicitly while
displaying results of hydraulic and cost calculations. User of LOOP can specify the status
of the pipe (i.e. whether existing or new). Accordingly, costs are computed and pipe
status is flagged in the outputs.

7. LOOP (Version 3.0) does not have any provision to specify minimum and
maximum pressures at nodes. In LOOP, the user has a flexibility to choose node specific
values of maximum and minimum pressures. This flexibility becomes necessary to play
around in identification of the economic design since the user may wish to relax pressure
constraints at nodes and stipulate higher pressures for industrial or fire prone regions.
If none are specified, then the program follows the general minimum and maximum
pressure criteria applicable to network. Appropriate indication is given in the output to
draw attention of the user to the nodes where the specified pressure constraints are not
met.

8. LOOP (Version 3.0) does not have a provision to declare different materials of
commercial pipe diameters while analyzing the distribution network. LOOP allows the
user to specify pipes belonging to a maximum of three different pipe materials and uses
this information while analyzing and sizing the distribution system. This addition is
expected to orient the computer based modeling closer to real world water distribution
system.

9. LOOP (Version 3.0) does not have flexibility to specify input data in different units.
Users of LOOP are however allowed to specify pipe length, pipe diameter, flow,
elevations, velocity, pressure and head in two types of units (MKS or FPS) and in various
combinations i.e. for example, velocity could be in feet/sec and pipe diameter in mm.

10. LOOP (Version 3.0) does not have any provision to allow display of Hydraulic
Grade Lines (HGLs) on screen. LOOP has this capability and provides the user an option
to prepare longitudinal profile of HGL for specified number of pipes both on screen as
well as on a dot matrix printer.

11. LOOP has several additional features to increase its user friendliness and
productivity significantly more than LOOP (Version 3.0). These improvements include,

• Window based menus with highlighted bar movement;

• Hierarchical menus;

• Context specific on-line help;

• More useful options in the data editor environment such as,

Basic mathematical operations

Search at all columns

Make column totals

Mark existing pipes and parallel pipes

Key to allow changes in number of pipes and nodes

Key to display features of function keys

Facility to enter head-discharge data as applicable for pumps directly into the
program ( LOOP has an in-built regression routine to make necessary polynomial
equations);

Improved and generalized file operations for copying, renaming/ moving,
erasing and saving files;

Other completely new features include,

More sophisticated check data option for finding data entry and syntax errors
Configuration option to allow the user to maintain data files in various sub
directories, declare name of organization, name of currency etc.

Automatic check for the equipment configuration and required DOS version.

Command line option to set up LOOP for different run time memory models,
printer paper specifications, help options etc.

Facility of an on-line electronic abridged user manual

Support to color monitors

Installation routine

While these improvements have been made in LOOP, its data entry environment
(e.g. tabular screens) has been maintained very similar to that of LOOP Version 3.0. The
features like insert / delete / copy etc. have been retained so as to give the users the same
feeling of familiarity. The users of LOOP Version 3.0 are hence expected to adjust very
well with LOOP.

2.0 General Data Requirements

The data required to run LOOP can be divided into four classes as follows,
Geometric data

• Node-pipe connectivity

• Length of all pipes

• Ground levels of all nodes

• Location of booster pumps and valves

Hydraulic data

• Average water demands at all the relevant nodes.

• Pipe resistance coefficient in terms of Hazen William's C or pipe roughness co-
efficient k in Darcy-Weisbach expression

Source data

• Elevations of all reservoirs

• Data on head-discharge curves for variable head reservoirs
Cost Estimation Parameters

• Available commercial diameters up to three material classes, with data on unit
cost and working pressure

• Newton-Raphson stopping criterion (viz. Maximum allowable error in flow
balance)

• Maximum and minimum pressure at nodes

• Design hydraulic gradient

3.0 Hardware Requirements

LOOP runs on all IBM-PCs or compatible machines such as PC (with two floppy
drives of 360 KB capacity), PC/XTs, PC/ATs, PC-386, PC-486 operating under MS DOS
versions 3.1 or above. Minimum RAM requirement is 640 KB for the execution of the
program to handle 1000 pipes. (For pipes less than or equal to 500, a minimum RAM of
512 KB is required). LOOP may not be able to handle 1000 pipes if any RAM resident
programs are kept active.

Use of a PC/AT is recommended. Presence of a math co-processor greatly helps
in reducing the computation time as the program does a significant amount of numeric
calculations and is thus strongly recommended.

LOOP runs only on computers with monitors having adapters such as Color
Graphics Adapter (CGA), Enhanced Graphics Adapter (EGA) and Video Graphics

Adapter (VGA). The program does not work, on a monitor with Monochrome Graphics
Adapter (MGA) and Hercules Graphics Adapter (HGA).

LOOP produces outputs on the disk and on dot matrix printer. The user can
further read the output file into any word processor and control the style, character size,
format etc. appropriate to his printer.

4.0 Installation Procedure

The contents of the floppy of LOOP for installation are as follows,

File Name

Description

INSTALL.BAT

This is the file for installation

LOOP41.EXE

This is the part of the compressed file for LOOP

LOOP42.EXE

This is the part of the compressed file for LOOP

Before installation of the program, make a copy of the program disk as a back-up.
Use the DISKCOPY command available in the DOS for this purpose. Put write-protect
tab on the master floppy disk as a precaution.

4.1 Installation on PC with Twin Floppy Drive

Before you run installation for twin floppy disk set up, make sure that you have
two 360 KB formatted blank floppy disks. The installation program, in fact "explodes" the
program from the compressed files LOOP41.EXE and LOOP42.EXE into two 360 KB
floppies.

Now boot the PC with DOS diskette in drive A:. Remove the DOS floppy and place
the Program Disk into drive A:. Type at the A: prompt

INSTALL f <ENTER>

The installation program now runs step by step. Follow the installation instructions
carefully. On completion of proper installation, you should have two 360 KB floppy
disks containing the "exploded" LOOP program files.

Contents of Program Disk-1 shall be,

File Name Description

LOOP.EXE

This is the executable version of LOOP

Contents of Program Disk-2 shall be,

File Name Description

LOOP4.BAT

This is a batch file to start LOOP

DEMO.LOP

This is the data file for demonstration

LOOP.HLP

This is the help file

4. 2 Hard 'Disk Installation for IBM-PC/XT or AT

Boot the machine and place the Program Disk in drive A. Now type at the C:
prompt (or D:/E: i.e. whichever hard disk drive in which you want LOOP to be
installed).

ATNSTALL h <ENTER>

The installation program now runs step by step. Follow the installation instructions
carefully. On completion of proper installation, you should have the "exploded" LOOP
program files in the directory LOOP on the hard disk. The contents of LOOP directory
are as follows,

File Name

Description

LOOP4.BAT

This is a batch file to start LOOP

LOOP.EXE

This is the executable version of LOOP

LOOP.HLP

This is the help file

DEMO.LOP

This is the data file for demonstration

PRTLOP

A utility file

4.3 Use of the Program

1. For proper functioning of LOOP, it is recommended that the contents of the
CONFIG.SYS file should contain the following commands,

FTLES=10
BUFFERS=30

LOOP'S graphics will not work well if DEVICE=ANSI.SYS is specified in the
CONFIG.SYS file.

2. For printing of outputs and graphs, you need to install printer with graphics
characters loaded in its memory.

To do so, for hard disk installation, set the path to your DOS directory by declaring
so in the AUTOEXEC.BAT file by: including following command line,

SET PATH = C: \ DOS

where DOS is the directory containing DOS files. Ensure that files such as
PRINT.COM, GRAPHICS.COM, GRAFTABL.COM are present in the DOS directory.

In the case of two floppy drive system, insert the DOS system disk containing files
such as PRINT.COM, GRAPHICS.COM and GRAFTABL.COM in drive A: and then type
the following commands at DOS prompt,

PRINT <ENTER>
GRAPHICS <ENTER>
GRAFTABL <ENTER>

In case, all these files are not present in the bootable DOS floppy, you have to place
the second DOS floppy into drive A: before typing some of the above commands.

3. For correct printing of outputs, ensure that the DIP (Dual In-line Package)
switches of your printer are set either to the option of IBM Graphics or Graphic
Characters. You mus t also select the switches correctly to specify the default page length
of the paper. Consult the section of Setting DIP Switches in your printer user guide to
understand the location of DIP switches and procedure to set them for different options.

For EPSON LX-800 printer and 11" size printer paper, the recommended DIP
switches are,

Switch

Function

Status

SW1-1

Type style

Normal DOWN (OFF)

SW1-2

Shape of Zero

Slashed UP (ON)

SW1-3

Character Table Paper

Graphics UP (ON)

SW14

Paper out of Detection

Active DOWN (OFF)

SW2-1

Page Length

1 1 Inches DOWN (OFF) Normal Mode DOWN

SW2-2

Cut-sheet Feeder

(OFF) OFF DOWN (OFF)

SW2-3

Skip-over Perforation

Line feed must be added to Carriage Return

SW2^1

Automatic Line Feed

DOWN (OFF)

e.g. USA UP (ON)

SW1-6

Country

SW-7

SW1-8

4.3 Setting up LOOP using Command Line Options

LOOP allows certain run time set-up parameters at its command line to add to the
flexibility of its use. These parameters can be set each time you run LOOP or this task
can be more easily done by designing appropriate batch file (as per user choice), such as
L00P4.BAT.

Contents ofLOOP4.BAT file, which is provided along with LOOP program, are as
follows,

CLS

LOOP IX /fl /r66 A3 /b3 /u /cRs /hY /iY

The explanation to the various command line options used is as follows,

Options not available directly from configuration

/ 1 or / m or /s : This is an important set up option for run time memory utilization of
LOOP. The implications are,

IX (large model) 1000 Pipes, 750 Nodes

Reservoirs (fixed and variable) 20
Booster pumps 20
PRVs20
Check valves 20

Maximum Commercial Diameters 30

/m (medium

model) 500 Pipes, 400 Nodes

Reservoirs (fixed and variable) 20
Booster pumps 40
PRVs40
Check valves 40

Maximum Commercial Diameters 30

/s (small model) 100 Pipes, 75 Nodes

Reservoirs (fixed and variable) 10
Booster pumps 20
PRVs 20
Check valves 20

Maximum Commercial Diameters 20

If you set up LOOP according to the size of the problem you wish to solve, then
the available memory is most optimally used. For instance, if you are operating with /s
or /m option, you can manage running LOOP in the RAM of 512 KB or keep a memory
resident program such as active in the background.

/ f n n is the number of logical fixed disk drives present in the system. The

default is one. For example, if-you have two separate 20 MB hard disks
say C: and D:, then you must specify set up option as If 2. If you have
one hard disk of higher capacity and have partitioned the same into three
logical drives say C:, D: and E:, then the correct set up option is If 3. Do
not specify higher number of logical fixed drives than the actual number
of drives present.

/ r n n is the total page length in lines (normally 72 for 12" page and 66 for 11"

page). Default is 66 corresponding to 11" paper length. (While invoking
this option you must have a compatible DIP switch setting of the printer
as earlier described)

/ 1 n n is the number of lines to be left as top margin. Default is 3.

/ b n n is the number of lines to be left as bottom margin. Default is 3.

The page layout in LOOP is as follows,

3 lines of Header (Fixed)
Top Margin (User Specified)

Bottom Margin (User Specified)
3 lines of Footer (Fixed)

In op la la denotes auto-numbering of pipe and node numbers during data
entry/editing, In disables auto-numbering, /u is the default.

/iN or iY During execution, LOOP prompts intermediate messages such as the

band width, number of iterations, unbalanced head/flow, run-time status
of PRVs/CVs etc. / iY option is the default. If these prompts are not
desired then the user can specify in the command line /iN.

This is a special switch to instruct LOOP to prepare outputs (both in
display as well as in printout) based on following sort conditions,

Nodes in the ascending order of residual pressures and pipes in the
descending order of the head loss gradient.

Outputs sorted in this form are desirable to focus quickly to the
low pressure nodes as well as high head loss pipes in the network for
suitable rectification.

The default condition will provide output for the pipes and nodes in the
order they are entered.

Options available otherwise from configuration but can be actuated from
command line:

/p LPT1 or

LPT2 Printer port. Default option is LPT1 .

/c Currency Symbol. For example /c $ initiates the currency symbol as $.

/ hy or / hn Sound during on-line help, y denotes yes and n as no. Default
condition stands for 'yes'.

If not stated in the command line, options specified in CONFIG.DAT
(explained in the next section) are used.

There is no restriction on the sequence of command line options and you can use
both upper and lower letters. There should not be however any space left between / and
the option (e.g. / 1 is invalid whereas l\ is a valid command line option).

5.0 LOOP Session

In this section we will make you familiar with the use of the LOOP using an
example DEMO. LOP data file. By the end of this session you should have working
knowledge of all the options and menus of LOOP. Here we will use the following syntax
for explaining the use of LOOP.

1. The Capital letters (e.g. LOOP4) means that you should type the text in a similar
way, either in lower or upper case, as specified in the manual.

2. The text when specified in the brackets (e.g. <ENTER>) corresponds to the key on
the keyboard which you are expected to press.

3. The text such as C:\LOOP> is the DOS prompt on your monitor (D:\ LOOP> \ if you
installed LOOP on drive D:). If you have a different DOS prompt, you can change to
similar prompt by adding a line PROMPT = SPSG in the AUTOEXEC.BAT file. (Consult
your DOS Manual if required).

4. The text in italics (e.g. User Manual) corresponds to an option in the menu.

To run LOOP now from the Hard Disk, boot the PC and change to the drive where
LOOP sub-directory is present and then change to sub-directory LOOP by typing the
following text at the root directory of your computer.

LOOP4<ENTER>

to invoke LOOP with default command line options listed above.

To run LOOP from twin floppy PC, boot the PC and activate the PRINT,
GRAPHICS and GRAFT ABL files as explained earlier. Place program disk-1 in drive A: and
in drive B: the program disk-2. Change to drive B: and at the DOS prompt type

LOOP4 <ENTER>

to invoke LOOP with default command line options listed above.

5.1 Configuration Screen

Now, LOOP will be loaded into the memory, and the opening flag of the program
will be shown. Press any key and a message will appear on screen, saying that the
CONFIG.DAT file not found in the current directory. Press any key other than <ESC> and
you are shown a Configuration Screen (refer to Figure 1). In configuration screen, you can
specify the drive and directory (i.e. path) of the program, data and output files.

For floppy drive installation, type the drive specifications in the configuration
screen, corresponding to each prompt, as follows,

For hard disk installation, the configuration screen, will show the directory path
C:\LOOP\ (assuming LOOP was installed in C:\LOOP directory) corresponding to each
prompt, as follows,

CD\LOOP<ENTER>

Now type,

Program Directory <A: \ >:
Data Directory <A: \ >:
Output Directory <A: \ > :

A:
B:
B:

Program Directory <C:\LOOP\> :
Data Directory <C:\LOOP\> :
Output Directory <C:\LOOP\> :

Leave the above three entries as blank so as to consider the default path
(i.e. C:\ LOOP \ ).

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Here, if you attempt to specify a non-existent directory or drive, then an error
message is flashed as "Path Not Found, Re-enter Proper Drive and/or Sub-directory".

In addition to above, you can also specify the name of the organization up to 20
characters (which appears at the bottom row of the screen) and currency symbol (which
appears against all cost related items). At the currency symbol, you can enter signs such
as $ and emulate symbol for Sterling Pounds by key combination of <ALT> and 156 (i.e.
keys 1, 5 and 6 from the numeric keypad). To enter symbols other then $ or £, you have
to emulate the sign using key combination of <ALT> and number (refer to ASCII table
for specific number) as typed from numeric keypad. This facility is however available
only from the command line option viz. /c. You can set up your printer by specifying
printer port either as <LPT1> or <LPT2>.

During the data entry environment, function key [Fl] is made available for popping
on-line help. The helpful text in a window can appear character by character with sound
or can be dumped on the screen without it. Normally, first time users of LOOP may like
the help to appear character by character so as to assimilate the helpful information in
a better manner. On regular use of LOOP however, the user may not like to be in such
a learning mode. You may therefore type either "Y" or "N" at the option of Sound on On-
Line Help? depending on your experience with LOOP.

Press <ESC> to save and exit the configuration options. At this step, a new file
called CONFIG.DAT is created in the program directory, which stores the configuration
information. In all future runs of LOOP, the present configuration is assumed (until you
make further changes) and hence the message "CONFIG.DAT file not found" does not
appear again. Now you will be once again shown the opening flag of the program and
on pressing any key, the first screen of LOOP appears, showing the Main Menu.

You must have observed that the option of currency, printer port and help sound
in configuration are also included as options in the command line setting of LOOP. It
must be noted however that for a particular run, command line options will always
override the options specified in the CONFIG.DAT file and hence you can set the run
time options for setting LOOP without actually changing the CONFIG.DAT file.

5.2 Main Menu

The topmost line in the first screen will always display LOOP Version 4.0 on the
left side, and current date (which is obtained from the system) on right side. The date
may need resetting if the system does not have a battery backup facility for maintaining
the internal clock. The bottom most line will display the name of the organization,
copyright and current path of data file (and name of data file if opened).

On the left-center portion of the screen is the Main Menu of LOOP (refer to Figure
2). This Main Menu shows options such as User Manual, File Operations, Solve Network,
Print Files, Configure and Quit.

A pointer in the form of a highlighted or inverse video bar (hereafter referred to
as highlighted bar) can be seen on the first item on the menu viz. User Manual. Below the

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Main Menu, a footer line is placed which explains how to move the highlighted bar
upand down i.e. using the <UP> and <DOWN> arrow keys and choose an option by
pressing <ENTER>.

By moving the highlighted bar, up and down on the main menu, you will note
that the second last line at the bottom of the screen gives a short description of the item
on which the highlighted bar is pointing. This description changes with the highlighted
bar position.

At this stage, let us try an example. Move the highlighted bar to the option User
Manual of Main Menu. Pressing <ENTER> gives you an opportunity to refer to an
abridged user manual. You have an access, to the keys such as <UP>, <DOWN>,
<PGUP>, <PGDN>, <HOME> and <END)> to browse through the helpful text or
alphabet keys from A-N for navigating quickly through selected sections of user manual.
On pressing <ESC> key, the Main Menu will be shown once again.

Now let us have a look at the other options on the Main Menu. The option File
Operations will lead you to another sub menu called File Menu (refer to Figure 3). This
sub menu helps you in performing file operations such as Load/Dir Data, Create/Edit Data,
Merge Data, Copy Files, Rename/Move Files, Erase Files, Save Data File, Check Data. Press
<ESC> to return to the Main Menu.

One important point to be kept in mind is that a data file should be either loaded
or created (i.e. opened) before choosing the Solve Network option or any options under
File Menu. As an exercise, try to choose the Solve Network option without loading or
creating any data file, the program flashes a message warning "Data file Not Opened.
Cannot Solve Network".

The option Solve Network will simulate/design the water distribution network
according to the data supplied and will show results in terms of tabular or graphical
form via Display Menu.

The option Print Files will lead you to another sub menu called the Print Menu.
This sub menu helps you to take a hard copy (i.e. print out) of the input data or output
files.

The option Configure allows you to re-configure the setup in which the program is
presently running. Pressing <ENTER>, the program shows the Configuration Screen,
where the set up information can be changed.

The option Quit will terminate the program and verify whether you want to save
the data file currently created or edited. After your response, you are taken back-to the
DOS prompt with closing screen similar to the opening flag.

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5.3 File Menu

After getting an idea of all the Main Menu options, we will explore the various
options of sub menus and try to learn each option by using the demonstration data file called
DEMO.LOP. Figure 4 shows a schematic diagram of this data file.

As a first step, select the File Operations option from the Main Menu. From the F: Menu,
select the Load/Dir Data option and a list of all data files (i.e. having extension .LOP) residing in
the specified data directory will be displayed (refer to Figure 5). Do n pile more than 60 data
files at one time in the data directory. In this screen, hereafter referred to as File Selection
Screen, a long highlighted bar appears and is placed on the name of the first data file. Pressing
the <DOWN>, <UP>, <RIGHT> or <LEFT> arrow keys, this highlighted bar can be moved to
the name of the data file which is to 1 selected. Then press <ENTER> to load the data file. In
this case, only one data file (vi DEMO.LOP) is present and the highlighted bar is already on
this file name. Pre <ENTER> and the DEMO.LOP data file will be loaded.

Now select the Create/Edit Data option of the File Menu and you will enter the data entry
editor with first data entry screen (General Information (Scr-D) of DEMO file. The description
on how to enter/edit data in the data entry screen is given later. Presently exit the editing
mode by pressing <ESC> to return to File Menu. Now select Create/Edit Data option once
again, and a dialogue box will appear prompting you to enter the data file name to be
created/edited. If the data file is already loaded (as above) then the currently loaded data file
name appears in the box, along with its full path. Sin* DEMO.LOP was last loaded, you will
see the string "C:\LOOP\DEMO" in the be assuming C:\LOOP\ is the current data directory.
At this stage, if you desire, you a specify a new data file name to create a new data file. To
do so, press <CTRL> arrow <END> to clear the box and then typing the new data file name.
If the new data file name does not exist, then a new file will be created. If you attempt
changing the currently data path in the box, then an error message is flagged "Path Cannot
be Changed".

You can also view data files selectively in the file selection screen, by specifying DC wild
characters * and ? in the file name. For example, type D* or D??????? to view and data files in
the current directory starring with alphabet D and having extension of .LOP

At this stage, type a new file called DEMOl in the dialogue box and press <ENTER
You will see a flashing message at the left-bottom of the screen "Save DEMO.LOP YES
(Y/N)". Press N (or space bar to toggle from YES to NO) and then press
<ENTER>. You will be shown the first data entry screen (General Information (Scr-D)
the new data file DEMOl .LOP. In order to exit from such an empty data file, you mi
fill the fields of number of pipes and nodes. Press <DOWN> arrow key to assign default
at these fields and then press <ESC> to return to File Menu.

Now choose the Load/Dir Data option and re-load the DEMO file. Before the DEN/ file is
loaded a warning message will appear such as,

File DEMOl .LOP already Opened, Attempting to Load Another File DEMOl .LOP

May Not be Saved

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Since we are not interested to save DEMO 1. LOP file, press any key to load
DEMO. LOP. If you want to save the currently opened file, then press <ESC> and save the
file before loading another file. A similar message will appear just as a matter of
caution. You will be prompted to save the data file whenever an attempt is made to
change the currently opened data file, to avoid accidental loss of data.

Now select the Copy Files option and a dialogue box will appear prompting to enter the
source data file name, which is to be copied. While entering the source file name, you can
specify the directory path or another drive if so desired. Extension .LOP is taken as default,
but you can specify any other extension as applicable to other types of files. For example, you
can do copy operations for output files by specifying .OUT extension.

For viewing files in the current data directory, you can type DOS wild card
characters such as * and ?. For example, clear the box (using <CTRL>+<END> keys) and type
* (or *.*) to view all the files (not restricted to .LOP) or type *.LOP to view only LOOP data
files. You can type D???????.OUT or D*.OUT to view all output files in the current directory
starting with alphabet D and having extension as .OUT. You will be shown the file selection
screen (similar to Load/Dir Data option) for viewing the files and having facility of the long
highlighted bar with cursor movement to select a particular file you want to make a copy.
You can even place the bar on directory name to navigate through the directories in the
specified drive.

If a data file is already loaded then its name along with full path will appear in the
dialogue box. Enter the desired file name and path as applicable, and press <ENTER>. If
this file does not exist then an error message will flash as 'Tile/Path Not Found". If this file
exists then another dialogue box will appear prompting you to enter the target file name.
Enter the target file name and press <ENTER>. The source file will be copied to the target
file. If the target file already exists then you are prompted whether to replace the previous
data file or not. If your response is yes (Y) then the file copy operation takes place.
Presently, the file name, DEMO should appear as a source file name. Press <ENTER> and
then type DEMOl as the target file name. Press <ENTER> and a copy of DEMO.LOP will be
made into DEMOl.LOP file.

Now, there is a word of caution. For the copying operation itself, LOOP requires at
least 3 to 4 KB of extra memory space. When you load LOOP with limited effective RAM
(e.g. 512 KB) and a medium or large network, adequate memory may not be available for
the purpose of copying large data files and the program may crash with overflow error
message. In such situations, use direct DOS operations for copying of files.

Select Rename/Move File option, a similar type of dialogue box will appear, as in the
copy option, but it will be empty. This option changes the specified (source) file name to the
target file name. Presently, type DEMOl as a source file name and DEMO'2 as a target file
name. The DEMOl.LOP file will now be renamed as DEM02.LOP file. Alf the general file
access facilities described in copy operations are available here.

On selecting the Erase option, an empty dialogue box will appear prompting you to
enter the file name, which is to be erased. Type DEM02 as the file to be erased and press
<ENTER>. You-are now asked about the confirmation by a flashing message

Erase File DEM02.LOP
NO

Are You Sure (Y/N) ?

Type Y or press space bar and then <ENTER> to confirm erasing of the
DEM02.LOP file. File DEM02.LOP is now erased or deleted from the disk. You should use
this option cautiously, as once a file is erased, it will not be restored again. But at the same
time if your data directory contains too many data or output files, it may be advisable to
use this option on unwanted files. All the general file access facilities described in copy
operations are available here.

The options under File Menu like Copy, Rename/Move and Erase, are very useful since
they allow you to perform copy, rename and erase operations on data as well as output files
without exiting LOOP and going to the DOS prompt. You cannot however alter (copy into,
rename/move or erase) the currently loaded data file. You can try. renaming or erasing
DEMO.LOP data file as an example and you will see an appropriate error message.

On selecting the Save option, you will be shown a dialogue box with the name of the
currently loaded file with its path. At this stage, you can change the file name as well as the
directory path or drive by typing the same in the dialogue box. Press <ENTER> to accept
the file name as DEMO. Since file DEMO.LOP already exists, you will be shown a
confirmation screen with a message 'File Already Present, Want to Overwrite? YES (Y/N)".
Type N or space bar and press <ENTER> not to overwrite the file.

On selecting the Check Data option, the currently loaded data file will be checked for
data entry mistakes. Data checking is a simple way to identify the obvious mistakes such as
typing errors, and thus avoiding the chances of "crashing" while solving the network. To
get a feel of check data option, go to the option Create/Edit Data, and press <ENTER> twice to
enter editing mode (now to edit DEMO.LOP file). You will see the first data entry screen -
General Information (Scr-I). Press <TAB> key to scroll into the second data entry screen.
The cursor will be positioned at pipe number 1 under the heading of "Pipe No.". Remove the
pipe number "1" using <DEL> and then press <ESC> for exiting data editing mode. Now,
select Check Data option. A flashing error message appears, "Pipe Number Should Not be
Zero. Check Position 1 in Pipe Screen". This is an example how the check data routine helps
you in identification of the type of error and also the probable place of error.

Press any key and then re-load the DEMO.LOP file using Load/Dir Data option. Select
Check Data option and now a message appears that "No Possible Data Entry or Syntax Errors
Found" (since you did not save the edited version of DEMO.LOP file and the original error
free DEMO.LOP file was reloaded, no error was detected).

In order to protect execution of LOOP from "foul" data files, it is a good practice
to run check data routine during the process of designing. The advantage of keeping
check data as a separate option is however to let the user have a quicker access to re-edit
the data file.

In addition to the above options, there is also an option for Merge Data. This is an
option where you can cojnbine two LOOP data files to prepare a single file. The
following are however the restrictions in the use of this option.

• the files to be merged must be created by LOOP

• merging implies that the first file specified is the mother file and the second file
is appended.

• in the merging process only the pipe data and node data is appended. The
number of pipes and nodes automatically increases in the first data entry screen.

• in the merging process, only pipe and node data from second data file is merged
and not the data on fixtures such as reservoirs, booster pumps and valves.

5.4 Simulate and Display Results

After exploring all the possible options in the File Menu, let us move to the solve
Network option of the Main Menu. LOOP could be run either in the Simulation mode (S)
or Design mode (D); S and D options are to be specified in the data file. (You will learn
more about this in Part II of the Manual). Presently DEMO has been set up for the
purpose of Simulation. Select Solve Network option and the program carries out simulation
of the network.

During simulation, LOOP displays first message such as "Do You Want to Check
Data Before Proceeding? YES (Y/N)" with another box pointing that data related to Pipe,
Node and other Misc. items have not been checked. Press <ENTER> to check data, and
you will see messages such as Checking Pipe Data, Checking Node Data and Checking
Misc. Data followed by flashing message as "Calculating.. ". At this point the network
solution algorithm starts functioning.

Now at the bottom of the screen a window with caption as "Simulation Messages"
appears. Here a number of intermediate messages are displayed such as Newton-
Raphson iterations, Bandwidth, Number of loops. Valve settings if any, Balancing head
and Flow errors if any, warning messages as applicable etc. (Refer to Figure 6). Consult
Part III for the technical information on some of these terms. In some cases, a beep comes
and you will be prompted to press any key to move further. After all calculations-nre
over, a message such as "Done .." appears and the Display Menu (refer to Figure .7) will
appear on the screen.

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Now let us explore the Display Menu. Here, options such as Display Results, Display
HGL, Save Output File are available.

On selecting Display Results option, another sub-menu called Result Menu appear
(refer to Figure 8) having options such as Pipe Details, Node Details, Pipe Cost,
Reservoir, Booster Pump, PRV/CV. Choose each of these options and familiarize with the
various items displayed on the screen. Wherever the information is not applicable for
options such as VH Reservoir and PRV/CV in the DEMO file), no output is shown

On selecting Pipe Details option, the details such as pipe number, its corresponding
"From" and "To" nodes, peak flow, pipe diameter, headloss, gradient (per 1000 length
units), length and velocity are displayed. You can use <PGUP> and <PGDN> key
scroll the pages, <UP> and <DOWN> keys to move one line up or down, and <HOMI and
<END> keys to reach beginning and end of the current output respectively, key facilities
are available for viewing all the options in the Results Menu. Press <TAB> to scroll to next
screen, where you are shown pipe number, its corresponding "From", "To" nodes,
diameter, friction coefficient (Hazen's C or Darc/s k), pipe material maximum
pressure, allowable pressure and pipe status (existing or parallel). If the maximum
pipe pressure exceeds the allowable pipe pressure, a flag such as "HI" (i.e High)
appears. In such cases, you could take action of installing PRVs or change positions or
change pipe class/materials. Press <ESC> to return to Results Menu.

On selecting Node Details option, the details such as node number, (peak) nod
flow, elevation, HGL and pressure are displayed. All source nodes (fixed head as we as
variable head sources) are marked as "S". Results about fixed head reservoirs ail
available in this menu itself. Flags such as "HI" and "LO" (i.e. High and Low respectively
are tagged wherever nodes do not meet the necessary minimum and maximum
pressures.

On selecting Pipe Cost option, the summary of cost for the water distribute
network in terms of diameter, pipe material, length (total), corresponding to ii cost and
cumulative cost are displayed. Press <TAB> and you will see additional such as pipe
number, diameter, pipe material, length and cost. These details pertain only to the new
pipes to be laid and not to the existing pipes.

If there are variable head reservoirs, then the option of VH Reservoir will show the
node number, four regression coefficients between Head (H) and Discharge (Q
(designated as PO, PI, P2 and P3) internally established by LOOP using H-Q
number of pumps, pump height (elevation), flow at each pump and head.

If there are booster pumps, then the option of Booster Pump will show the pipe
number, four regression coefficients between Head (H) and Discharge (Q) Designated
as BO, Bl, B2, and B3) internally established by LOOP using H-Q data, number of pump
flow at each pump and head.

If there were any PRV/CVs present in the system, then the option of PRV/CV will
show information such as "Pipe # containing a CV is operating/not operating" or "PRV
in Pipe # is Not Operational/Operational/ Acting as CV" etc.

Select Display HGL option from Display Menu and you will be asked to ent
sequence of pipe numbers for which HGL is to be viewed. Refer to Figure 9 carefully and
enter the pipe sequence as follows,

1,3,4,8,15,14,20,22,

You will now be shown on the screen a profile of HGL and ground level with
appropriate node and pipe labeling.

The rules for entering pipe numbers are as follows,

• pipe number must be ending with a , (comma) after the last pipe number
entered.

• pipe numbers should exist and the sequence of pipe numbers should represent
a continuous path (else an error message is given)

If you want to print the screen on the dot-matrix printer, make sure that printer,
is connected and set on with a paper. Press P for taking a printout of the section on the
screen. After printing is completed, press <ESC> to return to Display Menu.

On selecting Save Output File option, two options are displayed viz. Without Input
or With Input. Saving with input file may be desired for the final runs where you may be
interested to record the full details. For the present, choose the option of Without Input and
a dialogue box appears prompting you to enter the output file name, in which the results
will be stored. Presently, file name DEMO would appear with its path. Press <ENTER>
and the output results will be saved on the disk in the file called DEMO. OUT.

On selection of Print Files option from the Main Menu, a Print Menu is shown with
options such as Input Data and Output Result. Choose the option of Output Result. You
will have a dialogue box asking you to enter the file name to print. You can directly type
the file name as DEMO to instruct the program to print DEMO. OUT file. Additionally,
you can also view the files using the DOS wild card characters such as * and ? and select
the file to print. Type * and <ENTER> to view all the files with extension .OUT in the
output sub-directory. You will see only one file viz. DEMO. OUT. Select the file by
focusing the highlighted bar. The dialogue box would now have the file name as
DEMO.OUT with path as C:\LOOPV Press <ENTER>.

A message box now appears instructing you to set the printer on. (You could press
<ESC> at this stage if you want to abort printing). Set the printer on and then press a
key. Now you have another message box asking whether to pause between pages. Press
<ENTER>'to accept the default (printing with pause). The results are now printed page by
page on the printer and at end of each page you are prompted to press a key.

Now check the results of DEMO.OUT thus printed with the output file print out
given in the Appendix - A. These should exactly match.

5 . 5 Network Design

In order to get a feel about the diameter finding capability of LOOP, edit the
DEMO.LOP file (via. Create/Edit Data of File Menu) by following the instructions given below
carefully,

Press <TAB> to view the Pipe Data screen (Scr-II). Now place the cursor on the
first row on the Diameter column by using <ENTER> key four times.

The cursor should be focused now on diameter of 200. Delete the same using
<DEL>key.

Press F5 function key and type 24 at the prompt of "No. of Copies:". Press
<ENTER>

You should now see the entire Diameter column blank or devoid of any values.

Press <TAB> five times to reach the screen of Design Information-Scr XIII. Bring
the cursor to "Simulate or Design" using the <DOWN> key. Change S to D by over
typing.

Press <ESC> twice to return to the Main Menu.

Now we will solve the network under design mode to "find" the diameters in the
network such that the specified constraints of pressures are met and the cost of pipes is
minimum.

Choose the option of Solve Network. A message is flashed "Do You Want to Check Data
Before Proceeding? YES (Y/N)" with a message box pointing that data related to Pipe and
other Misc. items have not been checked. Note that the message at this stage does not point at
checking of Node Data as done in the first case. This is because you did not make any change in
items related to the Node Data Screen (Scr-III) and changes were made only at the Pipe Data
Screen (Scr-II) and Design Information Screen (Scr-XIII). This is an illustration of the dynamic
character of check data routine in LOOP. Press <ENTER> to check data.

You will see messages such as "Checking Pipe Data", "Checking Misc. Data", followed
by "Calculating Now at the bottom of the screen a window with caption as "Simulation
Messages" appears as described before (refer to Figure 6). Press any key and you will see
another box called "Design Messages" showing details such as Iteration Number, Feasible
Cost and Initial Cost. Cost corresponds to that of new pipes. Press a. key (or <ESC> to abort)
and you will be shown results of iteration #3 (costs of iteration #2 not shown since solution
being infeasible). The cost at iteration #3 will be 462.90 (*1000) as compared to 922.20 (*1000)
showing a reduction in the cost.

The design algorithm finds the economical diameter combination and displays the pipe cost in
the Design Message box only when it is feasible (else the iterations continue till a better
feasible solution is struck). Press a key each time to view the design process.

For each iteration in the design process, you will notice a change in the Newton-Raphson
iterations required in the Simulation Message Box.

At iteration #11, the feasible cost will be 427.90 (*1000) and a message such as
Done " appears at the Simulation Messages box. Press any key to reach the Display Menu.
Under the pipe details, you will see the "new" diameters "found" by LOOP. Check these
diameters with those inputted earlier and you will notice the following,

1. The cost of the network under automatic design is lower than the one earlier
provided (427.9 (*1000) as against 443.40 (*1000) leading to a saving of 3.5%.

2. The pressures at nodes in the automatic design are well within the limits specified.

Now edit the DEMO.LOP file via Create/Edit Data option of the File Menu and you will
see the diameters found "copied" under the Diameter column of Scr-II. If you save the file at
this stage then DEMO.LOP will be saved with these diameters.

At this point, change the Design Hydraulic Gradient in Scr-XIII from 5 to 8 and
solve the network. The initial cost displayed under design messages shall be 427.90 (*1000)
and not 922.20 (*1000) shown earlier. This is because LOOP uses the diameters found (for
Design Gradient of 5) as the initial condition. In this case, the solution will not change since
427.90 (*1000) happens to be the least cost solution.

This is a useful approach especially if you want to explore fine-tuning of the
solution by trying different design gradients successively. Alternatively, you may retain
diameters of only few selected links and let LOOP choose the remaining diameters for say
another design hydraulic gradient.

On the other hand, if you want to redesign the network from scratch for a new
hydraulic gradient of 8, you must set the diameters found in the earlier run to zero following
the editing procedure described before re-solving the network.

The relationship between design hydraulic gradient and pipe cost is non-linear but
generally low hydraulic gradients (e.g. 1) will lead to expensive solution compared to
high hydraulic gradient (e.g. 10). Another characteristics is that the solution for high
hydraulic gradient is relatively fast but the pipe velocities in few pipes will be on the
higher side. Conversely, if very low hydraulic gradient is used, then the solution time is
more and in some sections the pipe velocities are lower. One therefore, needs to adopt
a procedure of intelligent trial and error to settle on the best solution. The optimum may
be generally observed between design gradients of 2 to 5.

This tour of several menus and sub-menus completes our first exploration of
LOOP. Return to the main menu, by pressing <ESC> and choose the option Quit to exit
LOOP.

network. Figure 10 is a schematic diagram of the TEST network showing the location of
reservoir and demand nodes as well as locations of three pressure reducing valves. In
addition to this diagram, a print out of the input data has been enclosed in Appendix-B
to ease your data entry. This example has been adopted from Walski et al [13].

6.2 Numbering Technique

Now let us assign a number to each pipe and each node. The numbering should
be done for pipes and for nodes separately, usually starting from number one. Care
should be taken not to repeat the same number within the set of nodes or within the set
of pipes. The numbers assigned for the nodes and pipes in TEST network are shown in
the diagram (refer to Figure 10).

6.3 Resetting Configuration

Now that you are creating a new data file, it is recommended that you create a
new sub-directory for better housekeeping of data files. In the case of hard disk use,
make a sub-directory DATA by typing at C:\LOOP> (assuming LOOP is installed in
drive C:) prompt,

MD DATA <ENTER>
Now, load LOOP by typing,
LOOP4 <ENTER>

Choose the Configure option from the Main Menu and modify the options suitably.
Some of the important changes you could introduce at this stage are,

1. Directories: Declaring the newly created sub-directory LOOP/DATA as default for
input and output data files

2. Currency symbol: The default is Rs. But, you could enter abbreviation specific of
your country up to 3 characters.

3. Name of the organization: This will appear at the bottom line of the display
screen.

Once the Configure Screen is edited, type Y at "Save Changes: (Y/N)" to save the
screen and then <ESC> to end. Now the new configuration is written to file
(CONFIG.DAT) in the program directory. The new configuration options you indicated
shall now be used during future execution, till you reset the configuration once again. If
you had chosen N option at "Save Changes", then the new setting is kept operational only
till you exit this session of LOOP and the CONFIG.DAT file remains unchanged.

For floppy drive installation, place a new formatted disk in Drive B: to receive data
and outputs.

6.4 Data Entry Environment

Now choose the option of File Operations from the Main Menu. Select the Create/Edit
Data option. You will now see a file selection screen as in Figure 5 indicating that there
is no data file in the current directory. Press <ESC> to create data file, and you will have
a dialogue box prompting to enter the Data File Name. Enter the data file as TEST and
press <ENTER>. The program will take you into data entry editor showing the first data
entry screen (viz. General Information Scr-I).

The screen will typically show a top bar with program name and date and a
bottom bar indicating name of the organization, sponsor of the software and the name of
the current data file with its path.

The data entry screen has excellent data editing facilities made available through
preprogrammed function keys. Information on function keys can be seen at the bottom
portion of each data entry screen. The following table lists the different editing facilities
available.

Explanation to the various preprogrammed function keys is as below,

Function Keys

[Fl] Provides a pop up screen having context specific help. If sound is chosen in

the configuration option, then the help text is flashed on the window with
an emulated sound of a typewriter.

[SHIFT] Displays a text showing a summary of features of both ordinary keys as
+ [Fl] well as function keys reserved for editing facilities

[F2] Inserts a line at the cursor position.

[F3] Deletes a line at cursor position.

[F4] Appends (or adds) a line at the bottom of the data entry screen.

[F5] Copies a value down the cursor position in the same column. User is asked

to specify the desired number of times copying is to be done.

[F6] Does a mathematical manipulation to the value at the cursor such as,

* (Multiply)

/ (Divide)
+ (Add) or
- (Subtract)

To make use of F6 key, place the cursor under the field of interest. Now
press F6 key. At the bottom of the screen a prompt will appear as,
Equation?

Choose the scaling factor, e.g. if you are changing original data of length in
meters to feet it would need a scaling factor of 3.28. Hence, type at the prompt
the following,

3.28<ENTER>

This will lead .to another prompt on the same row asking number of rows to
be modified below the present location of the cursor.

F6 key has thus a potential use for doing mathematical manipulations in the
columnar data. Few additional tips must be however remembered while
making use of F6 key.

F6 key is available only to selected fields on the screen. For example, it is
inactive for operating on fields such as Pipe No., Node No. etc.

F6 cannot-be used to produce unacceptable numbers of questionable signs.
To illustrate this situation, consider variable like head (which is always
expected to be positive). If the original data is 100 and the user tries to
subtract 150 using F6 key, then the result will not be -50 but 50.

Due to restrictions on the significant number of the variables, use of F6
key will eventually lead to some loss of precision in the converted data. This
must be borne in mind especially if you attempt comparison between
original and modified results.

[F7] Displays the total of all values down the cursor position (including the value
at the cursor position). This facility is useful to obtain instant total of fields
such as flows, lengths etc.

[F8] This is a special key designated to mark the existing pipes in the Pipe Data
(Scr-II) screen.

[SHIFT] This is a special key designated to mark the parallel pipes in the Pipe Data
+ [F8] (Scr-E) screen.

[F9] Searches the specified value in the column where the cursor is positioned

and if the search is successful then shifts the location of the cursor to the
matching value.

[F10] This is a special key available only in the General Information (Scr-I) screen.

which when pressed allows the user to type over the number of pipes and
number of nodes.

It is to be noted that all of the above keys may not be available for each screen
or for each and every columns of a particular screen. For example keys such as [F5], [F7]
and [F9] are not available in the first and the thirteenth screens (i.e. General Information
(Scr-I) and Design information (Scr-XIII) respectively) and keys such as [F5] and [F6] do

not function on Pipe No., From Node and To Node of Pipe Data (Scr-II) screen and Node
No. of Node Data (Scr-III) screen.

Other Keys

Key to be Pressed

Facility Offered

<UP>

Move up one line

<DOWN>

Move down one line

<RIGHT>

Move right one character

<LEFT>

Move left one character or to the previous field

<ENTER>

Accept entry and move to the next field

<HOME>

Move to first entry in column

<END>

Move to last entry in column

<PGUP>

Go to previous page of the same screen

<PGDN>

Go to the next page of the same screen

<TNS>

Insert a space in between two characters

<DEL>

Delete a character at cursor position

Delete a character before cursor position

<TAB>

Move to next screen

Move to previous screen

6.5 General Information (Scr-I)

This screen accepts general information on the water distribution network like
number of pipes, number of nodes, number and material of commercial diameter,
type of hydraulic formula and units to be used for length, diameter, flow etc. A blinking
cursor will be positioned in the first row where you have to enter the Title of the
Project. A number of pre-programmed function keys are available for editing. Press
[SHIFT] and [Fl] keys to view the capabilities of these keys. After entering the data,
corresponding to each field as required, you can move to the next field by pressing the
<ENTER> or <DOWN> key.

To enter the data in this screen follow the steps as given below:

1. Title of the Project: Type the title of the project for data file identification
purpose only (Maximum length allowed is 44 Characters). Both alphabets and
numbers are allowed.

Enter TEST as the title of the project.

2. Name of the User: Type the name of user for data file identification purpose
only (Maximum length of 19 Characters).

Here you can enter your name. No numeric keys are allowed.

3. Number of Pipes: Enter the total number of pipes in the network. Maximum
number allowed is 1000 for large model, 500 for medium model and 100 for
small model. If you add new pipes or delete pipes in the Pipe Data (Scr-El) screen
then this total number of pipe changes automatically.

Enter 15 as applicable for this example.

Once you have entered the number of pipes, you cannot directly change the same
by typing over. This could be done by pressing [F10] function key first (refer to
the help menu) and then retyping immediately the new number of pipes. This
extra precaution has been kept to protect accidental loss of data.

4. Number of Nodes: Type the total number of nodes in the network. Maximum
number allowed is 750 for large model, 400 for medium model and 75 for small
model. If you add new nodes or delete nodes in the Node Data (Scr-III) screen
then this total number of nodes changes automatically.

Enter 13 as applicable for this example.

Once you have entered the number of nodes, you cannot directly change the same
by typing over. This could be done by pressing [F10] function key first and retyping
immediately the new number of nodes. As an example first move to the

next row by pressing <ENTER> and then by pressing <UP> arrow key, come under this field.
Now try typing over 13 with say 10 without pressing [F10] key. Press <ENTER>*and you
will find that the number 13 is unchanged.

5. Type of Pipe Materials Used: Type up to a maximum of 3 pipe materials
abbreviated into two alphabets each and separated by a / (forward slash).

A valid data entry for materials-such as Cast Iron, Mild Steel and HDPE may be,

CI/MS/HD

If you have only one material (say HDPE) but three pressure classes A, B and C, then
the data entry might be,

HA/HB/HC

LOOP uses this information to set up the commercial pipe data entry screens.

This specification is optional and in such case when this field is left blank "NA"
appears against related fields in the later screens (only if the data file is saved and
reloaded).

Enter CI as applicable in this example.

5. Number of Commercial Dia. per Material: Enter the number of commercial
diameters for each pipe material which are available for the design. If you are using 10
diameters of MUd Steel (MS) and 5 diameters of Cast Iron (CI), then you should type
data as follows,

10/5

corresponding to MS/CI/ typed under the type of pipe materials used. The order should
exactly follow the one followed in field 5.

The total number of commercial diameters which can be considered is 30 for large
and medium models and 20 for small model. Hence if you are specifying two pipe
materials, then, by default, the maximum number of commercial diameters per
material for large and medium model set up as 15 and for small model as 10.

Enter 3 as applicable in this example.

7. Peak Design factor: Enter Peak Factor applied to the average demand at all
demand nodes. The peak factor is only applied to demand (i.e. negative flows) and not
to flows contributing to the network (i.e. positive flows). Default is 1.

Press <ENTER> to accept the default value.

8. Type of Formula (1/2): 1 denotes Hazen William's formula and 2 corresponds
to Darcy-Weisbach expression. Default is Hazen William's formula i.e. 1.

Press <ENTER> to accept the default value.

The next seven data entry fields refer to the specification of units. User can make
combination to minimize data conversion efforts. For all units, there are two options,
designated as 1/2. To provide an instant explanation to what is implied by 1 or 2,
LOOP displays a small text line on the same row for every specification of units.

9. Unit of Pipe Length (1/2): 1 denotes that data on pipe length is in meters while 2
implies that the same is in feet. Default is 1 .

Enter 2 to indicate that the pipe length shall be entered in feet.

10. Unit of Pipe Diameter (1/2): 1 denotes that data on pipe diameters is in
millimeters while 2 implies that the same is in inches. Default is 1.

Enter 2 to confirm that the pipe diameters shall be entered in inches.

11. Unit of Pipe Flow (1/2): 1 denotes that data on pipe flow is in liters/sec while 2
implies that the same is in cubic feet/sec. Default is 1.

Press <ENTER> key to confirm that the pipe flow shall be entered in liters/sec.

12. Unit of Head (1/2): 1 denotes that head is in meters while 2 implies that the
same is in feet. Default is 1.

Enter 2 to confirm that the head shall be entered in feet.

13. Unit of Elevation (1/2): 1 denotes that data on node elevation is in meters while
2 implies that the same is in feet. Default is 1.

Enter 2 to confirm that the elevation shall be entered in feet.

14. Unit of Pressure (1/2): 1 denotes pressure in meters and 2 corresponds to pound
per square inch (psi). Default is 1.

Enter 2 to confirm that the pressure shall be entered in psi.

15. Unit of Velocity (1/2): 1 denotes velocity in meter/sec and 2 corresponds to
feet/sec. Default is 1.

Enter 2 to confirm that the velocity shall be entered in feet/sec.

After completing the details as appropriate to the TEST data file, press <TAB> to
move to the Pipe Data (Scr-II) screen.

6.6 Pipe Data (Scr-II)

This screen is exclusively for entering the pipe details like pipe numbers, its
starting or from node number, ending or to node number, and length of the pipe, etc.

Data entered should be strictly in the units specified under the captions. After
entering the data, corresponding to each column, you can move to the next column by
pressing <ENTER> key. If you are having more than fourteen pipes, then the data is
entered on the next page of the screen two. Press <PGUP> or <PGDN> to view the
previous or next page respectively.

Explanation to the various data entry items to complete this screen is as below. See
Appendix-B for the values to be entered for TEST network under each heading of this
screen.

1. Pipe No.: It is the number of the pipes in the network. It is recommended that pipe
numbers should be given in ascending order for better readability, but there is no
such restriction. There is an option of auto-numbering for the pipes in the command
line option and if opted for, LOOP displays the pipe numbers serially on pressing
<ENTER> or <DOWN> key. The user can overwrite, if necessary.

2. From Node: It is the number of the starting or "From" node from which the pipe
(as entered above) begins. The end at which a pipe starts is called "From Node".
The two ends of a pipe are termed as "nodes" and each node is assigned a unique
number. You can however have same node numbers as the pipe numbers.

3. To Node : It is the number of the end or "To" node where the pipe ends. The end
at which a pipe ends is called "To Node".

4. Length: Enter the length of pipe, in relevant units.

5. Diameter : Enter the diameter of the pipe in appropriate units if the pipe is
existing or if you wish to "force" your own option in the design. Leave the field
blank if you want LOOP to find the diameter. If you are choosing Simulation (S)
as the option in the Design Information (Scr-XIII) screen, (as applicable for this
example), then for each pipe, a diameter must be entered.

6. Hazen's/Darcy's Constant: Enter the appropriate value for the corresponding pipe.
Do not forget to distinguish between the old and the new pipe diameters. If no
value is entered, then the value specified in appropriate commercial diameter
screen is used as default.

7. Pipe Mater : Enter the material or pressure class of the pipe (in the two alphabet
abbreviation made in the General Information (Scr-I) screen). This information must
be entered if more than one pipe material is specified, otherwise the first pipe
material will be assumed for the pipe.

8. Exs/Parl : This field is not really a 'data entry field but a "status field" to declare
whether the pipe is existing (E) or a parallel pipe (P) is proposed. This can be done
by using [F8] as follows,

[F8] Marks pipe as existing (E). Pressing [F8] again erases the existing status.

[Shift] + [F8] Marks pipe as parallel (P). Pressing [Shift] + [F8] again de-marks the
parallel status.

Do not mark the field if pipe does not exist or no parallel pipe is to be proposed.
If you are planning to choose Simulation (S) as the option in Design Information
screen (Scr-XIII), do not mark any pipe as parallel. This is prompted as an error by
the check data routine. In case you wish to include parallel pipes in the Simulation,
you will have to create an extra pipe (i.e. two pipes having same "From" and "To"
nodes as well as length but different pipe number).

If the pipe is marked as existing then its cost is not calculated. If the pipe is
marked as parallel, then cost of the new parallel pipe is only calculated. It must be
remembered that if the pipe is marked as parallel, its status is shown as existing in
the output with another pipe (having same "From" and "To" nodes but a total new
pipe number) added.

After completing the appropriate data entry, press the <TAB> key, to move to the
Node Data (Scr-III) screen.

6.7 Node Data (Scr-III)

This screen is exclusively for providing the node related information such as water
demand, peak factor, ground elevation, etc. Note that all node numbers (including source
nodes), whether they contribute flow or not must be entered in this screen.

Data entered should be strictly in the units specified under the captions. After
entering the data, corresponding to each column, you can move to the next column by
pressing the <ENTER> key. If you are having more than fourteen nodes, then the data is
entered on the next page of the screen. Press <PGUP> or <PGDN> to view the previous
or next page respectively.

Explanation to the various data entry items to complete this screen is as below. See
Appendix-B for the values to be entered for TEST network under each heading of this
screen.

1. Node No : Type the node number for which the data is to be entered. The node
numbers, as given, while entering "From" and "To" nodes in the previous screen
(i.e. Scr-II) have to be used. The node numbers and other corresponding details can
be entered in any order but it is preferable to enter them serially. Remember to
enter the nodes including the source nodes. There is an option of auto-numbering
for nodes similar to that of pipe numbers in the Pipe Data (Scr-II) entry screen,

Which displays the node numbers serially on pressing the <ENTER> or <DOWN>
key. The user can however overwrite in case he does not prefer auto-numbering.

2. Peak Factor : This refers to the peaking factor applicable to the average flow. The
peak factor is to be entered only to the demand nodes (i.e. negative flow nodes)
and not to nodes contributing flows to the networks (i.e. positive flow nodes or
source nodes). Default is the peak factor entered in the General Information (Scr-I)
screen.

3. Flow : This refers to the average water demand at the corresponding node, in
relevant units. The value must be preceded by a negative sign for demand. All
flows arising from the nodes such as, .say a pump at a well which is known to
deliver water at a certain rate regardless of the HGL, should be specified with a
positive sign. These nodes may or may not be treated as source nodes. AH source
nodes (those declared in Scr-IV) flows must be left blank.

4. Elev: Enter the ground level elevation at the corresponding node in relevant units.

5. Min Pres : This is the minimum pressure desired at the corresponding node. The
default value for this node specific value is the minimum pressure specified in the
Design Information (Scr-XIII) screen.

6. Max Pres : This is the maximum pressure desired at the corresponding node. The
default value for this node specific value is the maximum pressure specified in the
Design Information (Scr-XIII) screen.

After completing the appropriate data entry, press the <TAB> key, to move to the
Number of Fixtures (Scr-IV) screen.

6.8 Number of Fixtures (Scr-IV)

This screen is exclusively for giving the details about the number of reservoirs,
booster pumps, pressure reducing valves (PRV) and check valves(CV) which will be used in
the design of the network. After entering the data, corresponding to each field as
required, you can move to the next field by pressing the <ENTER> or <DOWN> key.

To enter the data in this screen follow the steps as given below:

1. No. of Res. Nodes with Fixed HGL : The number of source nodes haxong fixed
HGL feeding the network.

Example of a fixed HGL node is a large reservoir where the water elevation does
not change significantly with demand.

Enter 1 as applicable for this example.

2. No. of Res. Nodes with Variable ; HGL : The number of source nodes where HGL
depends on the flow and hence is unknown. For all such nodes data on H-Q
curves must be available.

Example of a Variable HGL node is a pump feeding water from the source into the
network.

Enter 1 as applicable for this example.

3. No. of Booster Pumps : The number of on-line booster pumps.
Leave this field blank since there are no booster pumps in this example.

4. No. of Pressure Reducing Valves : The number of Pressure Reducing Valves
(PRV).

Enter 3 as applicable for this example.

5. No. of Check Valves : The number of Check Valves (CV).
Enter 1 as applicable for this example.

After completing the details as appropriate to the TEST data file, press <TAB> to move
to the Fixed Head Reservoir Node Data (Scr-V) screen.

6.9 Fixed Head Reservoir Node Data (Scr-V)

This screen is exclusively for providing the details about reservoirs with fixed HGL. If in
the Fixtures screen (Scr-IV), the number of fixed HGL reservoirs is declared as zero, then this
data entry screen will not be shown.

Data entered should be strictly in the units specified under the captions. After entering the
data, corresponding to each column, you can move to the next column by pressing the
<ENTER> key if. you are having more than fourteen reservoirs, then the data is entered on
the next page of the screen. Press <PGUP> or <PGDN> to view the previous or next page
respectively.

Explanation to the various data entry items to complete this screen is as below. See
Appendix-B for the values to be entered for TEST network under each heading of this
screen.

1. Node No: It is the node number for the fixed HGL source or reservoir.

2. lHead : HGL of the corresponding source or reservoir node in relevant units.

3. Ref Res ? (R/N): Enter "R" to indicate that the corresponding source node is a
reference node and "N" or blank if it is otherwise. From the number of fixed HGL
or variable HGL sources, there could be only one reference node in the system. The

hydraulic grade line elevations for the whole network are calculated starting with
that node. Refer to Part III for guidelines on how to choose a reference out of a
number of reservoirs.

After completing the appropriate data entry, press the <TAB> key, to move to
the Variable Head Reservoir Node data (Scr-VI) screen.

6.10 Variable Head Reservoir Node Data (Scr-VI)

This screen is for providing details about the sources with variable HGL (i.e. case
of direct pumping of water in the distribution system). If in the Fixtures screen, the
number of variable HGL reservoirs is declared as zero, then this data entry screen will
not appear.

Data entered should be strictly in the units specified under the captions. After
entering the data, corresponding to each column, you can move to the next column by
pressing the <ENTER> key. If you are having more than fourteen entries, then the data
is entered on the next page of the screen. Press <PGUP> or <PGDN> to view the
previous or next page respectively. For each H-Q pair of data more than one H-Q pair,
data on node number, number of pumps, number of points and reference reservoir need
not be entered.

Explanation to the various data entry items to complete this screen is as below.
Since there are no booster pumps declared for this example the values for TEST network
under each heading does not appear in Appendix-B.

1. Node No. : Enter the node number for the variable HGL source or reservoir.

2. No. of Pumps: Enter the number of pumps at corresponding source node installed

in parallel. If none entered, then one pump is assumed.

3. No of Max Pts : Enter the number of data points to be entered from the H(Head)

Q(Discharge) curve. At least 4 H-Q points to be entered.

4. X-Co-ord : Enter the data point on the X-axis i.e. Discharge (Q) in relevant units.

5. Y-Co ord : Enter the data point on the Y-axis i.e. Head (H) corresponding to the

data point on X-axis as entered, in relevant units.

6. Pump Ele : Elevation of the pump from the assumed datum for the whole network

(and not just elevation of pump above the elevation of corresponding source-node)
in relevant units.

7. Ref Res ? (R/N) : Enter "R" to indicate that the corresponding source node is a
reference node and "N" for otherwise. From the number of fixed HGL or variable
HGL reservoirs, there could be only one reference node in the system. The
hydraulic grade line elevations for the whole network are calculated starting with
that node.

Since we have not declared any of the fixed head reservoirs as reference for this
example, type R to declare'this reservoir as a reference reservoir.

After completing press the <TAB> key, to move to the next data entry screen. Since
in the Fixtures screen, we have declared the number of booster pumps as zero, the next .
data entry screen will not be Scr-VII but Scr-VETI. However for the sake of completeness,
we will describe Scr-VII as well.

6.11 Description of Booster Pumps (Scr-VII)

This screen seven is for providing the details about the booster pump location and
details. If in the Fixtures screen, the number of booster pumps is declared as zero, then
this data entry screen will not appear.

Data entered should be strictly in the units specified under the captions. After
entering the data, corresponding to each column, you can move to the next column by
pressing the <ENTER> key. If you are having more than fourteen entries, then the data
is entered on the next page of the screen. Press <PGUP> or <PGDN> to view the
previous or next page respectively. For each H-Q pair of data more than one H-Q pair,
data on pipe number, number of pumps and number of points need not be entered.

1. Pipe No. : It is the number of the pipe where the booster pump is located. The
direction of pumping is assumed in the direction of "From" to "To" nodes of that
pipe as entered in Pipe Data (Scr-II) screen.

2. Booster Pumps : It is the number of booster pumps at corresponding pipe
installed, in parallel. If none entered, then one pump is assumed.

3. No of Max Pts : This refers to the number of data points to be entered from the
H(Head)-Q(Discharge) curve. At least 4 H-Q points are to be entered. However,
recommended maximum H-Q points are 5.

4. X-Co ord : The data point on the X-axis i.e. Discharge (Q) in relevant units.

5. Y-Co ord (H): The data point on the Y-axis i.e. Head (H) corresponding to the
data point on the X-axis as entered, in relevant units.

After completing the appropriate details, press the <TAB> key, to move to the PRY
Description (Scr-VIII) screen.

6.12 PRV Description (Scr-VIII)

This screen is exclusively for giving the details about the PRV location and details,
if in the Fixtures screen, the number of PRVs is declared as zero, then this data entry
screen does not appear.

Data entered should be strictly in the units specified under the captions. After
entering the data, corresponding to each column, you can move to the next column by
pressing the <ENTER> key. If you are having more than fourteen PRVs, then the data is
entered on the next page of the screen. Press <PGUP> or <PGDN> to view the
previous or next page respectively.

Explanation to the various data entry items to complete this screen is as below. See
Appendix-B for the values to be entered for TEST network under each heading of this
screen.

1. Pipe No : Enter the pipe number where the PRV is located. Appropriate
consideration for the orientation of pipe in the network system should be given i.e
its "To" node must be on the downstream side of PRV. The direction of the PRV
is assumed in the direction of "From" to "To" nodes of that pipe as entered in Pipe
Data (Scr-n) screen.

2. Source Node No. : Enter the node number of the nearest or upstream source or
reservoir node from this PRV. If none is entered then the reference reservoir node
number is assumed.

3. D/S Head : Enter the operation head (that the PRV should maintain if operational),
in relevant units for the downstream side.

4. Resist Coeff : Enter the resistance coefficient of the PRV (the head loss of PRV is
assumed to be of form h=k*Q2). This must be developed in the appropriate units
declared for flow and head.

Read Part III of the manual for familiarization with the various terminologies on

PRVs.

After completing the appropriate details, press the <TAB> key, to move to the CV
Description (Scr-IX) screen. Since in the Fixtures screen, we have declared the number of
CV as zero, the next data entry screen will not be Scr-IX but Scr-X. However for the sake of
completeness, we will describe Scr-IX as well.

6.13 CV Description (Scr-IX)

This screen is exclusively for providing the details about the Check Valve (CV)
location.

Data entered should be strictly in the units specified under the captions. After
entering the data, corresponding to each column, you can move to the next column by
pressing the <ENTER> key. If you are having more than fourteen CVs, then the data is
entered on the next page of the screen. Press <PGUP> or <PGDN> to view the previous
or next page respectively.

Explanation to the various data entry items to complete this screen is as below.

1. Pipe No.: It is the pipe number containing the check valves. Appropriate

consideration for the orientation of pipe in the network system should be given i.e.
its "To" node must be on the downstream side of check valve. The direction of the
CV is assumed in the direction of "From" to "To" nodes of that pipe as entered in
Pipe Data (Scr-II) screen.

Read Part III of the manual to be familiar with the various terminologies on CVs.
After completing press the <TAB> key, to move to the Commercial Diameter (Scr-X)

screen.

6.13 Commercial Diameter ( Scr-X/XI/XII)

These screens are exclusively for providing the details about the commercial pipe
sizes for different pipe materials which are to be used for the design of the water
distribution network. Since in this case CI has been the only pipe material declared in the
General Information (Scr-I) screen, only one screen (viz. Scr-X) will be shown and the tile
of the screen will be CI Commercial Diameter (Scr-X).

Data entered should be strictly in the units specified under the captions. After
entering the data, corresponding to each column, you can move to the next column by
pressing the <ENTER> key.

Explanation to the various data entry items to complete this screen is as below. See
Appendix-B for the values to be entered for TEST network under each heading of this
screen.

1. Pipe Dia Int: The internal diameter of the available set of commercial diameters
for the particular class of pipe material, which is to be considered in the design of
network, in relevant units.

2. Hazen's/Darcy's Constant:Enter the appropriate value for the corresponding pipe.

3. Cost: The unit cost of the corresponding diameter pipe in specified currency per
unit length. This cost should include the cost of laying and jointing of pipe at the
site.

4. Allow Pre : The maximum allowable working pressure for the corresponding pipe
diameter and material in relevant units.

Depending on the number- of pipe materials, number of Commercial Diameter
screens will be shown (i.e. if only one pipe material is used then the Scr-XI and Scr-XII
will not be shown), on pressing the <TAB> key. Since we have declared only one pipe
material for this example, the next data entry screen will not be Scr-XI and Scr-XII but
Scr-Xni.

6.15 Design Information (Scr-XIII)

This screen is kept for the declaration of the water distribution network design
policies. The design process of LOOP can be controlled significantly by choosing the
various options from this screen. After entering the data, corresponding to each field as
required, you can move to the next field by pressing the <ENTER> or <DOWN> key.

To enter the data in this screen follow the steps as given below,

1. Newton-Raphson Stopping Criterion: This criterion refers to the
maximum allowable error in flow in any pipe while balancing heads. If this value is
too large then the balancing of heads and flows may not be proper. On the other
hand, if the value is too small, then the balancing may take quite a long time. The
default is 0.001.

Press <ENTER> key to accept the default value as applicable for this example.

2. Minimum Pressure: Enter the desirable minimum pressure at the nodes to be
maintained in the distribution network. Normally for urban areas the minimum
pressure to be specified varies between 7 meters to 17 meters. Default value here
is 17 meters.

Enter 40 (psi) as applicable for this example.

3. Maximum Pressure: Enter the desirable maximum pressure to be maintained in the
distribution network. Normally for urban areas the maximum pressure to be
allowed is between 40 to 80 meters. Default is 40 meters.

Enter 90 (psi) as applicable for this example.

4. Design Hydraulic Gradient:The design hydraulic gradient significantly influences
the initial design or pipe sizing of the network. Normally, some practical range is
used by designers as a guideline to design or master plan the looped water
distribution system. It is recommended that 5/1000 for smaller networks and
2/1000 for larger networks corresponding to peak flows are taken. Default value
is (2/1000).

Press <ENTER> key to accept the default value as applicable for this example.

5. Simulate or Design? (S/D): Indicate whether to "S"imulate or "D"esign the
distribution network. Option "S" is the default.

Press <ENTER> key to accept the .default value i.e. simulation of network as
applicable for this example.

After completion of this screen if the <TAB> key is pressed, then the General
Information (Scr-I) screen will be shown again or else press <ESC> to return to File .
Menu.

Thus after completing the data file TEST.LOP, exit the data entry editor using
<ESC>. Then save the TEST file by selecting the Save Data File option of File Menu.

Press <ESC> and return to the Main Menu. Select print option and print the data file
on the printer. Check all the data entered with the print out of the TEST data file attached in
Appendix-B. Since you have created a new file, you can opt to check the data using option of
Check Data from the File Menu to ensure that no syntactical errors have been made.

6.16 Check Data File

Whenever you create a new file, choose the option of Check Data from the File Menu
for syntactical errors. Check data option performs extensive set of tests on the data file. Some of
the checks include,

- whether there is a mismatch between minimum and maximum value (eg. you
cannot declare value of minimum pressure greater than the value ot maximum
pressure)

- whether there is any mismatch between node numbers and "From" and "To" node
declaration done for pipes

- whether the "From" or "To" node numbers or pipe numbers are repeated (e.g. you
cannot have two pipes having same numbers)

- whether the network connectivity is maintained (i.e. it is not fragmented)

- whether the diameters declared in all the pipe screens belong to commercially
declared diameters

- whether there is a duplication in the commercial diameters

- whether the source node is declared as the source node in node screen, (e.g.
source should have zero or positive flow as declared in Node Data (Scr-III). .

- whether the pipe number which appears in on-line booster pump screen, pressure
reducing valves screen and check valves screen appears in pipe data screen.

If the program points out any error, go back to data entry and correct the mistake. Since the
method of error trapping is step by step (i.e. not all at one time), repeat the Check Data
option till no error is pointed out.

Whether you ask for check .data in File Menu or not, the same is run automatically
during the design process. Thus, LOOP ensures that the input data file passed on to the
design routine is syntax error free and reasonable to the extent possible.

To understand, the role of check data, make some changes in your data file to learn
how check data prompts you for the data entry or syntax error.

6.17 Solve TEST Network

Having checked the data file, press <ESC> to return to Main Menu and choose the
Solve Network option.

You will see a sequence of messages just like while solving DEMO file but this time
you will have an opportunity to see typical valve operation messages sent to the screen.
Please refer to the description on PRVs and CVs in Part III of this manual to understand
the technical implications of valve setting and operation.

Save the output file from the Display Menu and print the output using the Print
Files option of the Main Menu. Check whether the results obtained match with the output
of TEST data file given in Appendix - B.

This tutorial with TEST.LOP must have given you confidence to try out your own
design strategies or introduce changes in the data file. There could be several possibilities
worth exploring. Following additional runs will show the flexibility of LOOP. These are,

1 . Add a check valve in pipe number 1 1 . Addition of a check valve will alter the flow
directions and quantities in the pipes. The results should show a general increase in
the node pressures and the input flow distribution of the two sources almost equal

as,

Source

Node 2

Node 11

Ips

Before Check valve Addition

45.51

69.97

After Check Valve Added

55.52

59.96

PRV/CV status will show an additional message,

Pipe #11 containing a CV is Operating

2. Strengthen the TEST network for a minimum pressure constraint of 75 psi at node
6 with a demand of 1.5 times the existing demand.

To achieve this requirement, place a booster pump in pipe 102 with following H-Q
characteristics,

X-Co ord

Y Co- ord

Ips-

84.95

116.71

42.475

329.18

28.317

368.50

0.0

400.00

To reflect the action of strengthening, do not forget to turn the status of all the
pipes to "Existing" so as to ignore the pipe cost calculations.

The results will show that a booster pump based on the theoretical requirements
of 92.01. Ips and a head of 67.60 ft may be ordered to meet this objective. A
summary of results will be,

Source

Pressure

Node 2

Node 11

Node 6

Ips

psi

Before Booster Pump

45.51

69.97

54.36

After Booster Pump

56.22

60.84

76.06

6.18 Computation Time Required

The design and simulation processes may take a couple of minutes if the network
is large (number of pipes and nodes) or if you are using a relatively slow computer. The
computation time increases with the presence of fixtures such as valves. Newton-Raphson
stopping criterion also influences the number of iterations and hence the computation
time.

Following is a comparative statistics for TEST data file as applicable to different

Type of PC Time Required for Design in

Seconds

PC .. 4.77 Mhz 180

PC/XT " 10Mhz_ 100

PC/AT 12 Mhz 10
with Maths Co-processor

PC/AT 16 Mhz 7
with Maths Co-processor -

* After check data and with /iN option in the command line and a Design
hydraulic gradient of 10.

PART-III

7.0 Technical Description

Computer based analysis and design of looped water distribution systems is
becoming increasingly popular in the recent times. Computer models are now accepted
as a reliable source of information for making engineering and operational decisions.

Given the network topology, supply and demands nodes and pipe characteristics,
the computer models can simulate flows in pipes, and pressures at nodes in looped water
distribution systems. The models may be used to,

1. Simulate alternative pipe size and layouts to determine which combination of pipes
can deliver adequate flow and pressure.

2. Simulate flows and pressures with alternative locations and capacities of pumps
and reservoirs to identify most effective combinations.

3. Conduct sensitivity analysis for future growth of demands and identify which of
the existing pipes need strengthening, cleaning or lining.

The subject of water distribution networks can be broadly divided into Simulation
and Design. Simulation refers to solving for flows and pressures in the network for the
given set of pipe sizes (pipes may either exist or may be assigned commercial diameters).
Design refers to finding pipe sizes (wherever pipe sizes are unknown) such that the flows
and pressures in the network are reasonably acceptable and yet the solution is
economical. It could be observed that simulation is a special case of design while design
includes simulation.

7.1 Simulation

A water distribution system model represents a set of nodes connected by pipes.
Nodes (or junctions) can be a point along a pipe where pressure heads are to be
calculated. Nodes can thus be placed anywhere along a pipe, but because too many
nodes tend to slow down the computation process and increase the memory
requirements, nodes are usually only assigned to intersections of pipes, changes in pipe
diameters, major water demands, dead end segments and reservoirs/sources. Nodes are
connected by pipes and pipes can contain fixtures such as check valves, pressure
reducing valves or booster pumps.

The central part of the computer model like LOOP, consists of the numerical
method used for solving the steady state flow equations. There are two types of
equations that are encountered in the looped water distribution systems:

1. Continuity - at each node the flow 'in' must be equal to the flow 'out'.

2. Energy - the nett head loss around each loop must be zero, and the head loss
between two reservoirs must be equal 'to the difference in the water level between the
reservoirs.

In the most general formulation, there is one continuity equation for each node
(balancing flows), one energy equation for each pipe (balancing heads), and one
pump/reservoir equation for each operating pump/reservoir. The system of equations
resulting on combination are solved using some numerical technique.

For the distribution systems encountered in practice, the number of loops is smaller than
the number of nodes (smaller by 25% [4]). Thus the computation work for balancing heads is
less than that for balancing flows. LOOP uses the method of balancing heads using Newton-
Raphson technique.

For the estimation of hydraulic gradient (S) through a pipe flowing full, LOOP allows
Hazen- William's and Darcy-Weisbach's expressions which in MKS units are given as,

Hazen-William's expression,

V = 0.85*C*R ' 63 *S 054 ...(1)

where, R is the hydraulic radius given by (D/4) where

D is the pipe diameter in m.
S is the hydraulic gradient in m/m

C is the Hazen-William's constant which depends on the pipe material.
Darcy-Weisbach expression,

V=S 05 x(2gxD) 05 xf 05 ...(2)
Where, f = Darcy's friction factor given by,

1/f 05 = -2 x log (k/(3.7 D) + 2.51/(R e x f ° 5 )) ... (3)

Where, k = roughness height in meters
Re = Reynolds's number

Equation (3) was originally proposed by Colebrook- White and is an implicit in nature
requiring iterative procedure to compute f. LOOP makes use of an explicit and
accurate form of this equation as developed by Jain [5] as,

1/f 5 = 1.14 - 2 x log (k/D + 21.25/ R e ' 9 )

(4)

7.1.1 Newton Raphson Method [2]

Consider a function of x i.e. F(x) as shown in Figure 1 1 and let 'a' be one of its
roots so that F(a) = 0. To find 'a' by trial and error procedure, assume that x is taken as
X for the first trial. Naturally F(x;) is not equal to zero. Let (6(x)) be the correction so that
F(x + (5 x)) = 0. Expanding by Taylor's theorem,

F(xO + F' ( Xi ) * 5(x) + F" ( Xi ) * 5(x) 2 / 2! + .... = ... (5)

in which F' and F" denote the first and the second derivatives of F(x) respectively with
the value of Xj substituted for x. If 5 (x) is small compared to x (as it will be when x
approaches a, the third and the subsequent terms of the expansion can be neglected
giving,

8(x)=-F(x»/F( xj ) ...(6)

This argument can be extended to a set of simultaneous equations involving more
than one variable. Thus for two variables x and y,

LetF 1 ,(x) = ..(7)
and F 2 (x) = ..(8)

be the two equations for the two variables x and y. If x, and y, are the two trial'values
and if (x) and (y) are the corrections, then as before,

F, (x, + 5 (x), y : + 5 (y)) = and ...(9)

F 2 (xj + 5(x), >1 + 5(y)) = ...(10)

Expanding and neglecting higher order terms,

Fi(xi, y l5 ) + [5(F0 / 5 ( Xl ) * 5 (x) +[5(F0 / 5( yi )] * 5 (y)=0 ...(11)

Fi(xi, y l5 ) + [5(F 2 ) / 5 (xl) * 5 (x) +[8(F2) / 8(yl)] * 5 (y)=0

(12)

Writing in the matrix form,

8(Fi) / 5 (xi) 8(Fi) / 5 (xi)
8(F 2 ) / 5 (xi) 5(F 2 ) / 5 (yx)

8(x)
8(y)

•(13)

Applying this formulation for the case of balancing heads, if Fi, F2 F3 ... Fi are the loop
headless equation values, then

8(F0 / 5 (Qi)
8(F 2 ) / 8 (Qi)

8(Fi) / 5 (QO
S(F 2 ) / 8 (QO

8(Fi)/8(Qi) 8(Fi)/8(Qi)

z 2

where, Zi, Z 2 , ... Z L are the corrections to the assumed values of 8 (Qi), 8 (Q 2 )...8 (QO
respectively.

It could be easily observed that the first matrix on the left hand side (called as the
Jacobian matrix) is symmetric in nature. The above simultaneous equations could be solved
using techniques such as Cholesky Decomposition. This technique has been employed in
LOOP. The equations could be repeatedly solved using updated values of Z till the Max(Zi)
is negligibly small. LOOP refers to this value as Newton-Raphson Stopping Criterion.

This method of balancing heads was first introduced by Martin and Peters [8] and has
been successfully used by Pitchai [9], Shamir and Howard [10], Epp and Fowler [4], Lam and
Wolla [7] etc. As the Newton-Raphson method considers all the loops simultaneously, the
convergence as far as the number of iterations are concerned is fast as compared to Hardy-
Cross method, however the computational work required per iteration is relatively more.
Additionally, the memory requirements are also higher.

7.7.2 Initialization of Flows

LOOP uses a strategy to automatically identify the loops using the concept of-
minimum path [4]. Having defined the loops, it sets the initial flows in pipes by
identifying the minimal spanning tree such that all demands are correctly balanced by the
source nodes. For pipes not included in the minimum spanning tree, zero initial flows are
assigned. The advantages of using this strategy as reported in [4] are,

1. In a spanning tree, by definition, any two nodes are connected by one and only
one path.

2. Using the minimal spanning tree with the length of each pipe equal to the
resistance of the pipe, pipes with the smallest resistance tend to get assigned zero
initial flows. This gives quite a reasonable approximation to the true flow which
in turn reduces the number of iterations required to find the final flow and even
more important, in practice, seems to assure convergence of the Newton's method.

7.1.3 Minimization of the Bandwidth

An effective means of substantially improving the computational efficiency of
obtaining solution to the above equations, is to band the Jacobian matrix. Epp and Fowler
[4] describe a method of banding the Jacobian by numbering the loops such that the non
zero elements in the equations are brought towards the diagonal, a procedure which is
called as minimization of the Band width. LOOP provides information on the band width
during the solution process if an option of /iY is used in the command line. Band width
depends on the network configuration, number of sources and in the case of multiple
sources, which source node is declared as the reference node.

The size of the Jacobian is computed as Bandwidth times the Number of loops.
This is in fact the real memory restriction on LOOP and not the pipe or node numbers!.
LOOP uses a dynamic memory management strategy to allocate maximum space
available to the storage of Jacobian during run time. If adequate storage is not available,
then a message "Matrix Overflow" is displayed, aborting the calculation process. In case of
such a message, check the RAM, network data and whether reference source is
properly assigned. If the data is correct and error cannot be resolved, then the only way
out is to divide the network into two independent networks and solve separately.

7.1.4 Source Nodes

Source nodes are nodes where water enters the network, and there must be at least
one of them. There could be two types of source nodes -one where the HGL is fixed (or
known) and other where HGL is variable (but with a known function of flow, such as
for pumps). For a variable HGL source node, it is not possible to fix both flow and the
HGL at that node, since the system is then "over-determined", and mathematically there
is no solution. If there is only one source (fixed or variable) node, then the HGL
throughout the network is calculated starting at that node.

If there are two or more source nodes, the calculations are more complex. Since the
HGL is known (or at least a function of flow) at each of the source nodes, the system
must be balanced in such a way as to maintain the implied HGL differences between the
various source nodes. This is done by varying the amount of flow such that each source
node contributes so as to produce the necessary HGL differences.

The LOOP program does this by finding a suitable set of pipes (preferably of large
diameters) between one of the source nodes and all the others. This "line" is called as
"pseudo-loop". If an energy balance is not possible to achieve in such a pseudo loop, then
LOOP sends a message "Energy Balance Violated - Trying to Resolve Conflict". The
program attempts resolving the conflict up to three times by "adjusting" the Jacobian, but if the
same cannot be resolved then sends a message to check the source data and abort the
calculation process. The probable error in such situations is normally in the H-Q data points of
variable head reservoirs or due to. very high HGL specified for closely spaced fixed head
reservoirs or due to specification of large diameter pipes between closely spaced
reservoirs.

If there are only two source nodes, then there is only one pseudo line, and
therefore, which source node is chosen as the reference node is not of concern. However, if
there are three or more source nodes, then the reference node should be the one that is most
"central" to the network, relative to the location of all of the source nodes. For example, there
are three source nodes, and two of them are close together, whereas the third one is on the
other side of the network, choose one of the two nodes that are dose together as the reference
node. This strategy greatly helps in the minimization of the bandwidth and hence reduction
in the RAM requirements.

For Variable Head Source Nodes, the formula for calculating the HGL is,

H = [ P + PiQ + P 2 Q 2 + P 3 Q 3 ] + P 4 - (15)

In the case of Variable Head Source Nodes, LOOP determines the constants, P Q , Pi, P 2
and P3 using least squares regression based on H-Q data taken from the pump
characteristics. There are three important points to be considered while specifying Variable
Head Source Data.

1. Be sure that the H-Q data strictly follows the units declared during entry of data.

2. Coefficient P 4 is not really computed and must be provided by the user since it
represents the elevation of the pump from datum so that the total HGL could be
computed. In the case of fixed head reservoir, Po represents the total HGL and
hence the user is not asked to enter data on P 4 separately.

For Booster pumps, the formula for calculating the HGL is,

H = [B + BiQ + B 2 Q 2 + B 3 Q 3 ] ...(16)

In case of booster pumps, these are fixed on-line (or on the pipe), fourth parameter, B4
can be estimated using the data on node elevations. The instructions for inputting H-Q data for
Variable Head Sources is also applicable for the booster pumps.

7.1.5 Pressure Reducing Valves and Check Valves

A pressure reducing valve (PRV) is designed to maintain a constant downstream
pressure regardless of the upstream pressure. The exceptions to this occurrence are,

1. If the upstream pressure becomes less than the valve setting, the valve becomes
inoperative and the analysis proceeds as if no PRV was present.

2 If the downstream pressure exceeds the pressure setting of the valve, the PRV acts
as a check valve preventing reverse flow. By preventing reverse flow, the PRV
functions as a check valve and allows pressure immediately downstream from the
valve to exceed its pressure setting. Thus, the PRV is used to reduce pressures in
portions of the pipe distribution system if the pressures are otherwise be excessive
or it may be used to control from which source of supply, or pipes, the flow comes
under various demand levels. The PRV acts as check valve until the upstream
pressure is reduced to critical levels by large demands, at which time additional
sources of water are drawn upon.

A PRV can be operational and non-operational. When non-operational, it is
assumed that the valve is wide open. Here, the PRV does have additional resistance over and
above that provided by the pipe itself. Most manufacturers report that this additional head
loss (due to resistance of the open valve) can be approximated by an equation of the form
h= K * Q 2 where h is the head loss and Q is the flow through the PRV. LOOP requires the
value of K (not to be confused with the pipe resistance coefficients k or C) which the user
should supply consulting the catalogue of the manufacturer. However, once the PRV
becomes operating, K is not relevant and so it may be generally set to zero as default.

Check Valves (CV) allow the flow of pipe in only one direction. If the check valve is
placed on the pipe, its direction is considered as the direction implied by From and To
nodes of the pipe. If the actual direction of flow is reverse of the assumed direction, the CV
is not operational. If a check valve is "operating", that is no water is flowing through the
pipe, LOOP removes the whole pipe from the system and repeats the whole calculation.
While "removing" the pipe, network gets fragmented, an appropriate message is shown.

In LOOP, it is assumed that the resistance factor K for flow through a CV can
either be zero (valve wide open)_or infinite (valve fully closed). If you want to simulate a
partially open valve or a valve with certain resistance factor, then declare this valve as a
PRV. Specify it in PRV data entry screen (Scr-VIII), and provide appropriate resistance
factor K and a very high requirement of downstream head. The PRV under this condition
will not be operating but the flow through PRV will suffer a loss of head depending on
resistance factor K and pipe velocity V.

The analysis of pipe networks containing PRVs and CVs must determine whether
the valves are in normal mode of operations (i.e. operating) or with any other conditions, _
and then apply appropriate techniques to obtain valid solution. In order to confirm that
valves are "operating", the network has to be solved, or almost solved. This is achieved' by
not allowing the check to be made on check valves and PRVs until the flows are almost
settled. LOOP sets a criteria for "Testing PRV/CV" when maximum (Q) falls within five
times of the Newton-Raphson stopping criterion.

When pressure reducing valves (PRV) are present, the above procedure of using

same loops for energy equations and corrective flow rates must be altered. Reasons why the
same loops cannot be used are,

1. The head drop across PRV cannot be expressed as a function of the (Q) circulating
through that pipe (in fact the head drop across PRV is independent of flow rate)

2. Continuity at some junctions is no longer satisfied if the 5 (Q) is assumed to
circulate through the pseudo loops starting at artificial reservoirs created by PRV to
another reservoir (or source pump) of the network.

For networks containing PRV, the individual values of 5 (Q) are assumed to
circulate around the basic loops of the network, which are defined identically in same
manner as if no PRV existed. The energy equations are then written around loops that
are defined by disconnecting the pipes containing PRV from their upstream junctions and by
replacing PRV with artificial reservoirs.

Consider the seven pipe network shown in Figure 12 in which PRV is placed in
pipe 2 (Refer to Jepson [6] for more details). The corrective flow rates 4Qi) and 4(Q2) are
assumed to circulate around two basic loops containing pipes 1, 2, 3, and 4; and 6, 7, and 2,
respectively. The energy equations are written around the loops defined by dashed lines
in Figure 12. One of the loops is encompassing both basic loops and other is a pseudo
loop that proceeds from the artificial reservoir replacing the PRV, in the most direct route
to the supply reservoir. The energy equations are,

Fl= Ki (Qoi + AQi) al + K6 (Qo6 + AQ 2 ) a6 +

K 7 (Q 07 + AQ 2 ) a7 - K 3 (Q 03 - AQif -

K4(Qo4 + AQi) a4 = ...(17)
E2 = K 2 (Q02 + AQi . AQ 2 f - K 3 (Q 03 - AQj)" 3 -

K 5 = (Q 05 f + Hi- (HGL)i = ...(18)

In order to simulate the PRVs correctly, LOOP finds a path between the node
upstream from the PRV to some source node. The path may go through other PRVs, but
if so, it is ensured that the same goes through the PRV in one direction only, namely,
from the downstream side of the PRV to the upstream side. However, in certain network
configurations, it is not possible to find such a pathway. User is asked to provide the
node number of the source node which in most cases could simply be the reference node
itself.

7.2 Handling Pipes with Different Materials/Pressure Classes

LOOP allows the user to specify up to three types of pipe materials while
describing the pipe network. The user can specify pipe materials (in the abbreviation of two
alphabets) such as Cast Iron (CI), Mild Steel (MS) or Asbestos Cement (AC) etc. If HOPE
pipes of different pressure classes are to be used then, user may declare pipe

materials as HI, H2 and H3 indicating pipes of three different classes. It is necessary that the
user inputs pipe materials for each pipe in the system; however if none is specified then
LOOP assumes that the first pipe material has been used.

LOOP uses the information on pipe material in determining the pipe sizes.

7.3 Parallel Pipes

LOOP allows the user to indicate pipes where a parallel pipe may be proposed.
LOOP adds an extra pipe to the total number of pipes internally and proceeds with
simulation and design. The material of the parallel pipe is taken as that of the existing
or primary pipe.

7.4 Network Geometry Constraints

Some of the important restrictions for the use of LOOP related to network
geometry are as follows,

1. Number of parallel pipes cannot exceed 40% of the total number of pipes declared
or total number of pipes declared plus the number of parallel pipes cannot exceed the
maximum allowable number of pipes. In such a case, an error message appears as

Too Many Parallel Pipes in Network
Change Memory Model or Simplify Network

For example, if you run LOOP with 300 pipes and medium model, then you cannot
define more than 40% of 300 pipes viz. 120 parallel pipes. Further, if you are having 400
pipes with medium model, then you cannot define more than 25% of 400 pipes viz. 100
pipes as parallel pipes since the sum total (400 plus 40% of 400 pipes) exceeds the
maximum allowable 500 pipes.

3. In LOOP, each node in a network can be at most connected to 4 pipes. In practice,
we rarely have networks where each node is connected to more than 4 pipes. Generally
the average connectivity for a node will be around 2 or 3. For instance, as an extreme,
some nodes may have only one pipe connected while there can be some nodes with more
than 6 pipes connected; averaging out the connectivity equal to or less than 4.

If the average connectivity of the network increases beyond 4, then an error
message is flashed as,

Too Many Pipes Connected to Node/s, Simplify Network

In such instances, the system may be decomposed by introducing additional zero
demand nodes with short lengths to reduce the connectivity.

7.5 Design

Design of a looped water distribution network involves selection of an appropriate pipe
diameter for every pipe, so that the water can be transported without violating specified
hydraulic constraints and the desired minimum pressures maintained at nodes. Options for the
location and capacity of source nodes are normally relatively few and are hence prefixed. The
usual process is one of trial and error, where the engineer attempts a set of pipe sizes and
checks the hydraulic conditions to see if they are adequate. If not the engineer changes the
pipe sizes heuristically (or changes the pump locations and capacities if possible) to arrive
at a workable alternative. Cost estimates, on which a final decision has to be based are made for
each feasible alternative for the purpose of ranking.

It seems at first that the computer programs could directly solve the network for the
required pipe sizes. However, this cannot be done however for real problems because for any
problem of significant size, there are many combinations of pipes that are possible.
Therefore, evaluation of a very large number of options to arrive at the best solution is needed.
The problem is further compounded because pipes are available only in discrete sizes and cost-
headloss relationships are nonlinear. Theoretically, as stated by Templeman [11], the
optimization problem does not have a truly global least cost solution. The best we can
expect therefore is identification of a good sub-optimal solutions.

Numerous researchers have proposed methods for determining optimal pipe sizes in
real world water distribution systems (refer to Walski [12] for a comprehensive review).
Although all the methods can provide some useful insight for selecting pipe diameters, they
may not give practical and at the same time good sub-optimal solutions. It is not surprising
therefore, that there are indeed very few pipe sizing (or design) computer models developed.

Apart from the total costs, there are many facets of pipe sizing that can only be
addressed qualitatively by an engineer using judgment, insight and experience. As Walski et al
[14], in the paper on "Battle of Network Models - Epilogue" states, "...while the pipe network
optimization programs can assist the engineer in selecting pipe sizes, a great deal of engineering
judgment and experience is needed to determine the low cost workable solution. ... Locations of source
nodes and capacities are portions of the problem which can be cited as examples of users intervention

7.5.1 Pipe Sizing Algorithm used by LOOP

The algorithm used for finding sizes of pipes in LOOP is only a tool to provide a good
starting solution for the user to further improve on the solution. The procedure -followed
is heuristic and is derived from the work reported by Dixit and Rao [3]. This., method has
been found to be working quite well when compared to other theoretically rigorous
methods. (Refer to Dixit [2] for a detailed comparison) and is hence expected to result in a
quick and good starting solutions. The algorithm followed in LOOP is an extension of
this approach by introducing certain generalities. Reasons for relying on such an approach
are as follows,

1. The extended approach is easy to understand and to explain to the design

engineer.

2. The algorithm is quite efficient in terms of solution rime as well as memory
resources as compared to techniques such as Linear Programming (LP) or Non-
linear Programming (NLP); the latter consideration being quite critical in terms of
implementation of the code of LOOP on Personal Computer (PC) environment.

3. The algorithm considers diameters in the discrete commercial form (unlike non-
linear programming) and does not presupposes a flow distribution (unlike in linear
programming).

4. The computational performance of the algorithm excels the other optimization
techniques in terms of its robustness and speed. The optimal solutions obtained by this
algorithm compare favorably (in some instances are found even better) with
those obtained by other optimization techniques.

The premise of the algorithm is as follows,

The main constraint in the sizing of pipes is that the pressures at the nodes should
satisfy the specified minimum, say h m i n . If the head at a source is H A then pipe sizes
should be selected such that,

H, - (head loss due to friction) >= hmin ... (19)

If headloss due to friction is represented by Darcy-Weisbach expression, then (in
MKS units).

( H, - 1W / L >= f Q 2 / [ (2 g D) * (3. 14 * D 2 /4) 2 ] ... (20)

or for economical solution,

(H,-h min )/L = fQ 2 /(12.1 *D 5 ) ...(21)

where,

L is the length of the flow path between the source and node where pressure, at least
equal to hmin, is to be maintained. Equation (21) could be directly used for sizing diameter D of
length L spanning between one source and a demand node.

For a looped system consisting of several pipes and sources, equation (21) cannot -be
used as a one step procedure since it is difficult to identify both critical node and its,., path
length with respect to multiple sources. There could be some situations however where a
good estimate of path length can be obtained by studying the pipe layout.

It could be noted that the term [ (H, - hmi n )/L ] represents the maximum allowable
hydraulic grade line in the system. Normally, it is the experience that some practical range
is used by designers as a guideline to design or master plan the looped water

distribution system. Walski et. al. [13] recommend that a guideline of 5/1000 and 2/1000
for smaller and larger networks -respectively. It is pragmatic that the designer uses a
prefixed or preferential value as maximum allowable grade line (MaxHyGrd) rather than
attempting the exact calculation of [ ( Hs - h,^ )/L ]. The philosophy of using a guideline
.'estimate is more towards relying on actual experience of the designers on the behavior
of the networks. Equation (21) could be then expressed as,

MaxHyGrd = f Q 2 / ( 12. 1 * D s ... (22)

hence rearranging,

Qi = ( MaxHyGrd* 12.1 *D S !/f) 0S ...(23)

It could be interpreted that for a network with known pipe sizes D„ and specified or
targeted MaxHyGrd, the flows through the pipes should be as close to Q, so as to lead to a
cost-effective solution. In such a case, Qi in various pipes may be considered as near optimal
flows.

For networks with unknown pipe sizes then, a following iterative algorithm could be

used,

1. Prepare a table of diameters (Dj) and corresponding optimal discharges (Q,) for all
the commercial diameters which are used in the design.

2. Assume maximum available commercial diameters in all new or "diameter free"
pipes (where diameters have not been forced) and analyze the system for pressures
at nodes. If the solution is not feasible, terminate the computational process. User
has to change the inputs on source nodes and/or pressure constraints. If the
solution is feasible, then compute the cost of all new pipes in the network and
proceed.

3. For every new pipe, compare the actual flow in the pipe with the corresponding
optimal flow developed in step 1. The criteria for updating the diameter D, is as
follows,

Firstly, out of the set of commercial diameters, two diameters, say D ( and D (i+1)/ are
found such that,

Q 1<a bs(Q)<Q 1+1 ..(24)

where abs(Q) denotes the absolute value of flow through the pipe.

The next task then is to find the new size of the pipe i.e. whether D ; or D (i+1) . For this
purpose, following proximity rule is used,

If Qi < abs(Q) < (Q; + Q (i+1) ) 12 then D = D }

And

If Q i+1 > abs(Q) > (Q ; + Q (i+1) ) 12 then D = D i+1

•(25)
.. (26)

If abs(Q) is so low that abs(Q) < Q, (suffix 1 denotes the smallest given
commercial diameter), then D is set equal to Dj. Similarly, it' abs(Q) is higher
than QNComm (suffix NComm denotes the largest given commercial diameter),
then D is set to Ekmm)-

4. Update all new pipe diameters as per step 3 and re-analyze the system for
pressures. If the solution is feasible, then the cost of all the new pipes in the
system is computed and compared with the previous feasible cost. If the cost is
reduced, move to step 3.

If the cost remains unchanged for two successive computational cycles, then
terminate the algorithm, assuming that all flows are now falling in the
corridors of optimal discharge.

If an infeasible solution is struck while updating the pipe sizes, make it feasible
by incrementing pipe by one size for all new pipes, which connect to the nodes
having low pressure.

The final solution of the algorithm is a feasible solution. Normally, if a proper
value of MaxHyGrd is set then not more than five to six (generally three)
iterations of diameter updates are required to reach a cost-effective solution.

It could be observed that the pipe sizing process followed in this algorithm is of
successive approximation and can be effectively controlled by the user using a design
value of MaxHyGrd. If a higher value of MaxHyGrd is used, then pipe sizes found are
relatively smaller, with possibilities of infeasible solution being struck in the second or
third diameter update. If a lower value of MaxHyGrd is used, then the pipe sizes
tend to be larger and the final solution though feasible may correspond to more
expensive solution. User can thus generate different starting solutions using this
algorithm for subsequent "touches" or "improvements".

References

1. Bhave P.R. "Analysis of Water Distribution Network - Part I, II and III", Journal of Indian
Water Works Association, No. 2, 3 and 4, 1981.

2. Dixit M. "Analysis and Design of Water Distribution Network", Dissertation submitted to
Department of Civil Engineering, Indian Institute of Technology, Bombay, India, 1990

3. Dixit M. and Rao B.V. "A Simple Method in the Design of Water Distribution Network*",
Afro- Asian Conference on Integrated Water Management in Urban Areas, Bombay, India,
December, 1987.

4. Epp R. and A.G. Fowler "Efficient Code for Steady State Flows in Networks", Journal of
Hydraulics Division,American Society of Civil Engineers,Vol.96, No. HY1, January 1970

5. Jain A.K. "Accurate Explicit Equation for Friction Factor", Journal of Hydraulics
Division, American Society of Civil Engineers, Vol. 102, No. HY5, May, 1976

6. Jeppson R. and A. L. Davis "Pressure Reducing Valves in Pipe Network Analysis",
Journal of Hydraulics Division, American Society of Civil Engineers, Vol. 102, No.
HY7,July, 1976.

7. Lam C.F. and M.L. Wolla "Computer Analysis of Water Distribution Systems : Part I
Formulation of Equations", Journal of Hydraulics Division, American Society of Civil
Engineers, Vol. 98, No. HY2, February, 1972.

8. Martin D. W. and Peters G. "The Applicability of Newton's Method to Network Analysis

by Digital Computer", Journal of Institution of Water Engineers, Vol. 17, 1963.

9. Pitchai R. "A Model for Designing Water Distribution Pipe Network", thesis presented to
Harward University, at Cambridge, Mass, in 1966, in partial fulfillment of the
requirements for the degree of Doctor of Philosophy.

10. Shamir U. and C.D.D. Howard "Water Distribution System Analysis", Journal of
Hydraulics Division, American Society of Civil Engineers, Vol. 94, No. HY1, January,
1968

11. Templeman A. Discussion of "Optimization of Looped Water Distribution System", by
Quindry et. al., Journal of Environmental Engineering Division, American Society of Civil
Engineers, Vol. 208, EE3, 1982.

12. Walski T.M., "State of the Art : Pipe Network Optimization", Computer Applications in
Water Resources, Ed. H.C. Torno, American Society of Civil Engineers, NY, New York.

13. WalskiT.M, Johannes. Gessler and J. W. Sjostrom '"Water Distribution Systems :
Simulation and Sizing", Lewis Publishers'; 1990

14. Walski T.M., E. Downey Brill, Jr., Johannes Gessler, I.C. Coulter, R. M. Jeppson, K.
Lansey, Han-Lin Lee, J.C. Liebman, Larry Mays, D.R. Morgan and L. Ormnsbee,
"Battle of the Network Models : Epilogue", Journal of Water Resources Management,
American Society of Civil Engineers, Vol. 113, No. 2, March 1987.

LOOP Version 4.0

InputData File :DEMO.LOP

Page # 1

Title of the Project
Name of the User

Loop Design Sample
Sumito

Number of Pipes
Number of Nodes

24
20

Type of Pipe Materials Used : CI/

Number of Commercial Dia per Material : 6/

Peak Design Factor : 2

Newton-Raphson Stopping Criterion Ips : .001

Minimum Pressure m : 7

Maximum Pressure m : 30

Design Hydraulic Gradient m in km : 5

Simulate or Design? (S/D) : S

No. of Res. Nodes with Fixed HGL : 1

No. of Res. Nodes with Variable HGL :

No. of Booster Pumps :

No. of Pressure Reducing Valves :

No. of Check Valves :

Type of Formula : Hazen's

Pipe
No.

From
node

To
node

Length
m

Diameter
mm

Hazen'sConst

Pipe
Material

Status(E/P)

300

800.00

200.0

110.00000

350.00

100.0

110.00000

500.00

150.0

110.00000

600.00

75.0

110.00000

720.00

75.0

110.00000

700.00

100.0

110.00000

750.00

50.0

110.00000

700.00

50.0

110.00000

350.00

100.0

110.00000

500.00

100.0

110.00000

600.00

150.0

110.00000

800.00

75.0

110.00000

900.00

150.0

110.00000

550.00

50.0

110.00000

800.00

100.0

110.00000

500.00

150.0

110.00000

650.00

100.0

110.00000

800.00

75.0

110.00000

LOOP : Looped Water Distribution Design Program- (C) The World Bank / UNDP.

LOOP Version 4.0 Input Data File : DEMO.LOP Page # 2

Pipe
no.

From
node

To
node

Length
m

Diameter
mm

Hazen's
Const

Pipe
Material

Status
(E/P)

500.00

75.0

110.00000

350.00

150.0

110.00000

900.00

100.0

110.00000

1200.00

100.0

110.00000

100

500.00

150.0

110.00000

200

350.00

200.0

110.00000

Node Data

Node
No.

T*» 1

Peak

Flow
lps

Elevation
m

Min Press
m

Max Press
M

2.00

-2.600

15.00

7.00

30.00

2.00

-3.400

15.00

7.00

30.00

2.00

-1.500

15.00

7.00

30.00

2.00

-1.300

15.00

7.00

30.00

2.00

-1.200

15.00

7.00

30.00

2.00

-1.500

15.00

7.00

30.00

2.00

-1.200

15.00

7.00

30.00

2.00

-1.300

15.00

7.00

30.00

2.00

-1.200

10.00

7.00

30.00

2.00

-2.600

10.00

7.00

30.00

2.00

-1.300

10.00

7.00

30.00

2.00

-1.400

10.00

7.00

30.00

2.00

-1.500

10.00

7.00

30.00

2.00

-1.800

10.00

7.00

30.00

2.00

-1.600

10.00

7.00

30.00

2.00

-2.100

10.00

7.00

30.00

2.00

-1.300

10.00

7.00

30.00

300

2.00

0.000

10.00

7.00

30.00

100

2.00

15.000

10.00

7.00

30.00

200

2.00

20.000

10.00

7.00

30.00

Source
Node

Head m

Ref Res?
(R)

300

40.00

LOOP : Looped Water Distribution Design Program- (C) The World Bank / UNDP.

LOOP Version 4.0 Input. Data File: DEMO.LOP Page # 3

Commercial Diameter Data

Pipe Dia
Int. (mm)

Hazen's
Const

Unit Cost
Rs / m length

Allow Press
in

Pipe
Material

50.0

110.00000

10.00

100.00

75.0

110.00000

20.00

100.00

100.0

110.00000

30.00

100.00

150.0

110.00000

40.00

100.00

200.0

110.00000

50.00

100.00

250.0

110.00000

60.00

100.00

LOOP : Looped Water Distribution Design Program- (C) The World Bank / UNDP.

Output Data File : DEMO. OUT 10 August 1991

Page # 4

Echoing input Design Variables

Title of the Project

Loon Design Samnle

Name of the User

Sumito

Number of Pipes

Number of Nodes

Type of Pipe Materials Used

CI/

Number of Commercial Dia per Material

Peak Design Factor

Newton-Raphson Stopping Criterion lps

.001

Minimum Pressure m

Maximum Pressure m

Design Hydraulic Gradient m in km

Simulate or Design? (S/D)

No. of Res. Nodes with Fixed HGL

No. of Res. Nodes with Variable HGL

No. of Booster Pumps

No. of Pressure Reducing Valves

No. of Check Valves

Type of Formula

Hazen's

Looped Water Distribution Network Design Output

BandWidth = 3

Number of Loops = 5

Newton Raphson Iterations = 6

Pipe Details

Pipe

From

Flow

Dia

HL/ 100m

Length

Velocity

no.

node

(lps)

(mm)

(m)

(m/s)

300

22.600

200.0

3.22

4.02

800.00

0.75

4.245

100.0

1.86

5.32

350.00

0.54

9.621

150.0

1.68

3.36

500.00

0.54

2.586

75.0

5.17

8.62

600.00

0.59

1.245

75.0

1.60

2.23

720.00

0.28

3.534

100.0

2.65

3.79

700.00

0.45

0.234

50.0

0.55

0.73

750.00

0.12

0.186

50.0

0.33

0.48

700.00

0.09

2.715

100.0

0.81

2.32

350.00

0.35

1.580

100.0

0.33

0.85

500.00

0.20

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

Output Data File : DEMO.OUT . 10 Augus.t 1991

Page # 5

Pipe Details cont'd

Pipe

From

Flow

Dia

TJT

TUT / T flA™

HL/ lUUm

Length

Velocit

no.

node

(Ips)

(mm)

(ml

(m)

(m/s)

15.64

150.0

4.96

8.27

600.00

0.89

1.360

L 75 -°

2.10

2.62

800.00

0.31

13.760

150.0

5.86

6.51

900.00

0.78

0.240

50.0

0.42

0.76

550.00

0.12

4.004

100.0

3.82

4.77

800.00

0.51

9.236

150.0

1.56

3.11

500.00

0.52

5.200

100.0

5.03

7.74

650.00

0.66

1.636

75.0

2.95

3.69

800.00

0.37

0.964

75.0

0.69

1.39

500.00

0.22

11.000

150.0

1.51

4.30

350.00

0.62

3.200

100.0

2.84

3.15

900.00

0.41

4.200

100.0

6.26

5.21

1200.00

0.53

100

15.000

150.0

3.82

7.64

500.00

0.85

200

20.000

200.0

1.12

3.21

350.00

0.64

Pipe Pressure Details

Pipe

From

Dia

Hazen's

Pipe

Max Press

Allow Press

Status

No.

Node

(mm)

Const

Material

(m)

(E/P)

300

200.0

110.00000

30.00

100.00

100.0

110.00000

21.78

100.00

150.0

110.00000

21.78

100.00

75.0

110.00000

20.10

100.00

75.0

110.00000

19.92

100.00

100.0

110.00000

21.78

100.00

50.0

110.00000

20.10

100.00

{ 8

50.0

110.00000

14.93

100.00

100.0

110.00000

19.13

100.00

100.0

110.00000

19.56

100.00

150.0

110.00000

19.56

100.00

75.0

110.00000

21.22

100.00

150.0

110.00000

21.22

100.00

50.0

110.00000

15.78

100.00

100.0

110.00000

15.78

100.00

150.0

110.00000

18.04

100.00

100.0

110.00000

18.04

100.00

75.0

110.00000

18.04

100.00

75.0

110.00000

15.78

100.00

150.0

110.00000

15.36

100.00

100.0

110.00000

13.85

100.00

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

Output Data File : DEMO.OUT 10 August 1991 Page # 6

P ipe Pressure Details cont'd

Pipe
No.

From
Node

To
Node

Dia
(mm)

Hazen's
Const

Pipe
Material

Max Press
(m)

Allow Press
(m)

Status
(E/P)

100.0

110.00000

13.85

100.0

100

150.0

110.00000

25.04

100.0

200

200.0

110.00000

25.68

100.0

Node Details

Node
No.

Flow
(lps)

Elev.
(m)

HGL

(m)

Pressure
(m)

-5.200

15.00

36.78

21.78

-6.800

15.00

35.10

20.10

-3.000

15.00

34.92

19.92

-2.600

15.00

33.32

18.32

-2.400

15.00

34.13

19.13

-3.000

15.00

34.56

19.56

-2.400

15.00

29.93

14.93

-2.600

15.00

29.60

14.60

-2.400

10.00

28.04

18.04

-5.200

10.00

23.01

13.01

-2.600

10.00

31.22

21.22

-2.800

10.00

25.78

15.78

-3.000

10.00

25.36

15.36

-3.600

10.00

23.85

13.85

-3.200

10.00

21.02

11.04

-4.200

10.00

17.60

7.60

-2.600

10.00

25.09

15.09

300S

22.600

10.00

40.00

350.0.00

100

15.000

10.00

35.04

25.04

200

20.000

10.00

35.68

25.68

ipe cost Summary

Diameter
(mm)

Pipe
Material

Length
(m)

Cost
(1000 Rs)

Cum. Cost
(1000 Rs)

50.0

2000.00

20.00

75.0

3420.00

68.40

88.40

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP
Output Data File : DEMO.OUT " 10 AugusH991 Page # 7

Pipe Cost Summary cont'd

Diameter
(mm)

Pipe
Material

Length
(m)

Cost
(1000 Rs)

Cum. Cost
(1000 Rs)

100.0

5450.00

163.50

251.90

150.0

3350.00

134.00

385.90

200.0

1150.00

57.50

443.40

Pipe-Wise Cost Summary

PineNo

Diameter
(mm)

Pipe
Material

Length
(m)

Cost
(1000 Rs)

Cum. Cost
(1000 Rs)

200.0

800.00

40.00

100.0

350.00

10.50

50.50

150.0

500.00

20.00

70.50

75.0

600.00

12.00

82.50

75.0

720.00

14.40

96.90

100.0

700.00

21.00

117.90

50.0

750.00

7.50

125.40

50.0

700.00

7.00

132.40

100.0

350.00

10.50

142.90

100.0

500.00

15.00

157.90

150.0

600.00

24.00

181.90

75.0

800.00

16.00

197.90

150.0

900.00

36.00

233.90

50.0

550.00

5.50

239.40

100.0

800.00

24.00

263.40

150.0

500.00

20.00

283.40

100.0

650.00

19.50

302.90

75.0

800.00

16.00

318.90

75.0

500.00

10.00

328.90

150.0

350.00

14.00

342.90

100.0

900.00

27.00

369.90

100.0

1200.00

36.00

405.90

150.0

500.00

20.00

425.90

200.0

350.00

17.50

443.40

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

LOOP VERSION 4.0

Input Data File; TEST.LOP

Appendix B

LOOP

Version 4.0

Program for Design of
Looped Water Distribution Network

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

LOOP Version 4.0 Input Data File: TEST.LOP Page # 1

Title of the Project .

Example 1 from Wadiso

Name of the User

Sumito

Number of Pipes

Number of Nodes

Type of Pipe Materials Used

CI/

Number of Commercial Dia per Material

Peak Design Factor

Newton-Raphson Stopping Criterion

Ips

001

Minimum Pressure

psi

Maximum Pressure

psi

Design Hydraulic Gradient ft in 1000ft

Simulate or Design?

(S/D) :

No. of Res. Nodes with Fixed HGL

No. of Res. Nodes with Variable HGL

No. of Booster Pumps

No. of Pressure Reducing Valves

No. of Check Valves

Type of Formula

Hazen's

Pipe Data

Pipe
No.

From
Node

Node

Length ft

Diameter
in

Hazen's
Const

Pipe
Materia

1800.00

8.0

100.00000

1000.00

10.0

100.00000

1000.00

8.0

100.00000

10.00

8.0

100.00000

1000.00

8.0

100.00000

10.00

8.0

100.00000

1000.00

8.0

100.00000

101

2000.00

12.0

100.00000

102

1500.00

10.0

100.00000

111

5000.00

12.0

100.00000

112

1500.00

8.0

100.00000

114

1500.00

8.0

100.00000

122

10.00

8.0

100.00000

123

1500.00

8.0

100.00000

124

1500.00

8.0

100.00000

Status
(E/P)

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

LOOP Version 4.0 Input Data File: TEST.LOP Page # 2

Node

1NO.

Peak

Flow
Ips

Elevatio

n ft

n tt

Min
Press psi

Max Press

rSl

1.00

0.000

950.00

40.00

i \ i \ i \ i \

90.00

1.00

0.000

910.00

40.00

90.00

1.00

-3.160

905.00

40.00

r\/~\ /~\/~\

90.00

1 f\f\

1.00

/"\ r\r\r\

0.000

950.00

40.00

r\/~\ /~\/~\

90.00

1.00

r\ f\f\f\

0.000

A^A f\f\

920.00

40.00

90.00

1.00

-5.050

890.00

40.00

90.00

1.00

-4.730

890.00

40.00

90.00

1.00

0.000

890.00

40.00

90.00

1.00

0.000

890.00

40.00

90.00

1.00

0.000

870.00

40.00

90.00

1.00

-3.160

870.00

40.00

90.00

1.00

-4.730

870.00

40.00

90.00

1.00

-94.650

850.00

40.00

90.00

Fixed Head Reservoir Data

Source
Node

Head ft

Ref Res ?
(R)

1050.0

Variable Head Reservoir Data

Source

Nos.

X-
Coord
Ips

Y-Coord

Pump Elev.

Ref Res ?

Node

Pumps

Pts

Ft.

(R)

84.950

113.84

950.00

56.630

133.85

28.320

146.30

0.000

151.20

Pressure Reducing Value Data

PRV
Pipe
No.

Source
Node

Oper. Head
Ft

Resist
Coeff.

1027.00

0.00000

1027.00

0.00000

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

LOOP Version 4.0 Input Data File;,TEST.LOP Page

Pressure Reducing Valve Data

PRVPipe Source Oper. Resist
No Node Head ft Coeff.

122 11 1007.00 0.00000

Commercial Diameter Data

PipeDia. Hazen's U "'5" st Allow Press Pipe

Int. (in) Const length psi Material

8.0 100.00000 \ 9 - 0.00 rTrT

10.0 100.00000 30 000

12.0 100.00000 28. .00 Ci

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

Output Data File : TEST.OUT . 10 August 1991

Page

Echoing Input Design Variables

Title of the Project

Example 1 from Wadiso

Name of the User

Sumito

Number of Pipes

Number of Nodes

Type of Pipe Materials Used

CI/

Number of Commercial Dia per Material

Peak Design Factor

Newton-Raphson Stopping Criterion

Ips :

.001

Minimum Pressure

psi :

Maximum Pressure

psi :

Design Hydraulic Gradient ft in 1000ft

Simulate or Design?

(S/D) :

No. of Res. Nodes with Fixed HGL

No. of Res. Nodes with Variable HGL

No. of Booster Pumps

No. of Pressure Reducing Valves

No. of Check Valves

Type of Formula

: Hazen's

Looped Water Distribution Network Design OutPut

BandWidth = 2

Nuinber of Loops = 3

NeVvton Raphson Iterations = 6

Pipe Details

Pipe

From

Flow

Dia

HL/lOOOft

Length

Velocity

No.

Node

(Ips)

(in)

(ft)

(ft/s)

-17.309

8.0

4.88

-2.71

1800.00

-1.75

59.659

10.0

9.04

1000.00

3.86

3.160

8.0

0.12

1000.00

0.32

39.605

8.0

0.13

12.55

10.00

4.01

39.605

8.0

12.55

1000.00

4.01

59.775

8.0

0.27

26.89

10.00

6.05

59.775

8.0

26.89

1000.00

6.05

101

J»

45.510

12.0

4.51

2.25

2000.00

2.05

102

62.819

10.0

14.92

9.95

1500.00

4.07

111

69.970

12.0

24.98

5.00

5000.00

3.15

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

Output Data File : TEST.OUT 10 August 1991 Page # 5

Pipe Details cont'd

Pipe

From To

Flow

Dia

HLflOOQft

Length

Velocity

No.

Node Node

dps)

(in)

(ft)

(ft/s)

112

13 15

49.501

8.0

28.45

18.97

1500.00

5.01

114

15 16

4.846

8.0

0.38

0.26

1500.00

0.49

122

Pipe Flow Zero due to Valve

Action

10.00

123

34 35

0.000

8.0

0.00

1500.00

0.00

124

35 36

34.875

8.0

14.87

9.92

1500.00

3.53

Pipe Pressure Details

Pipe
No.

From
Node

To
Node

Dia
(in)

Hazen's
Const

Pipe
Material

Max Press
(psi)

Allow Press
(psi)

8.0

100.00000

58.74 HI

0.00

10.0

100.00000

57.02 HI

0.00

. 8.0

100.00000

78.14 HI

0.00

8.0

100.00000

57.19 HI

0.00

8.0

100.00000

60.37 HI

0.00

8.0

100.00000

57.02 HI

0.00

8.0

100.00000

62.59 HI

0.00

101

12.0

100.00000

58.74 HI

0.00

102

10.0

100.00000

58.74 HI

0.00

111

12.0

100.00000

56.52 HI

0.00

112

8.0

100.00000

57.19 HI

0.00

114

8.0

100.00000

57.19 HI

0.00

122

Pipe

Flow

due

Valve Action

123

8.0

100.00000

60.37 HI

0.00

124

8.0

100.00000

62.59 HI

0.00

Status
(E/P)

Node
No.

Flow
dps)

Elev. (ft)

HGL

(ft)

Pressure (psi)

3
6

11 S
13

45.510

0.000
-3.160
69.970
0.000

950.00

910.00
905.00
950.00
920.00

1050.00

1045.49
1030.58
1075.36
1050.37

43.35

58.74
54.44
54.34
56.52

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

Output Data File : TEST.OUT . 10 August 1991

Page # 6

Node No.

Flow Ops)

Elev. (ft)

H G L

(ft)

Pressure (psi)

-5.050

890.00

1021.92

57.19

-4.730

890.00

1021.54

57.02

0.000

890.00

1021.79

57.14

0.000

890.00

1021.27

56.91

0.000

870.00

1009.25

6037

-3.160

870.00

1050.25

78.14

-4.730

870.00

1009.25

60.37

-94.650

850.00

994.37

62.59

Pipe Cost Summary

Diameter

Pipe

Length

Cost (1000

Cum. Cost

(in)

Material

(ft)

Rs)

(1000 Rs)

8.0
10.0
12.0

CI
CI
CI

10830.00
2500.00
7000.00

209.02
72.25
283.50

209.02
281.27
564.77

Pipe
No

Diameter
(in)

Pipe
Material

Length

(ft)

Cost
(1000 Rs)

Cum. Cost
(1000 Rs)

8.0

1800.00

34.74

10.0

1000.00

28.90

63.64

8.0

1000.00

1930

82.94

8.0

10.00

0.19

83.13

8.0

1000.00

1930

102.43

8.0

10.00

0.19

102.63

8.0

1000.00

1930

121.93

101

12.0

2000.00

81.00

20193

102

10.0

1500.00

4335

246.28

111

12.0

5000.00

202.50

448.78

112

8.0

1500.00

28.95

477.73

114

8.0

1500.00

28.95

506.68

122

8.0

10.00

0.19

506.87

123

8.0

1500.00

28.95

535.82

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

Output Data File : TEST.OUT . 10 August 199 1

Page # 7

Piperwise Cost Summary cont'd

Pipe

Diameter

Pipe

Length

Cost (1000

Cum. Cost

(in)

Material

(ft)

Rs)

(1000 Rs)

124

8.0

1500.00

28.95

564.77

Variable Head Reservoir Statistics
Node No.

p , p . No Pump Ht Flow/Pump Head

Pump (ft) (lps) (ft)

11 151.20

-.396E-01 -.471E-02 -.284E-08 1

950.00

69.97 125.36

PRV/CV Status

1 PRV in Pipe # 22 is Not Operational

2 PRV in Pipe # 23 is Not Operational

3 PRV in Pipe # 122 is Acting as CV

LOOP: Looped Water Distribution Design Program - (C) The World Bank/UNDP

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